ref: 3648afda1694fcb4d6fe6625b14f5a3f8bc29c38
dir: /docs/bugs_and_glitches.md/
# Bugs and Glitches These are known bugs and glitches in the original Pokémon Crystal game: code that clearly does not work as intended, or that only works in limited circumstances but has the possibility to fail or crash. Fixes are written in the `diff` format. If you've used Git before, this should look familiar: ```diff this is some code -delete red - lines +add green + lines ``` Fixes in the [multi-player battle engine](#multi-player-battle-engine) category will break compatibility with standard Pokémon Gold/Silver/Crystal for link battles, unless otherwise noted. This can be avoided by writing more complicated fixes that only apply if the value at `[wLinkMode]` is not `LINK_COLOSSEUM`. That's how Crystal itself fixed two bugs in Gold and Silver regarding the moves [Reflect and Light Screen](#reflect-and-light-screen-can-make-special-defense-wrap-around-above-1024) and [Present](#present-damage-is-incorrect-in-link-battles). ## Contents - [Multi-player battle engine](#multi-player-battle-engine) - [Perish Song and Spikes can leave a Pokémon with 0 HP and not faint](#perish-song-and-spikes-can-leave-a-pokémon-with-0-hp-and-not-faint) - [Thick Club and Light Ball can make (Special) Attack wrap around above 1024](#thick-club-and-light-ball-can-make-special-attack-wrap-around-above-1024) - [Metal Powder can increase damage taken with boosted (Special) Defense](#metal-powder-can-increase-damage-taken-with-boosted-special-defense) - [Reflect and Light Screen can make (Special) Defense wrap around above 1024](#reflect-and-light-screen-can-make-special-defense-wrap-around-above-1024) - [Moves with a 100% secondary effect chance will not trigger it in 1/256 uses](#moves-with-a-100-secondary-effect-chance-will-not-trigger-it-in-1256-uses) - [Belly Drum sharply boosts Attack even with under 50% HP](#belly-drum-sharply-boosts-attack-even-with-under-50-hp) - [Berserk Gene's confusion lasts for 256 turns or the previous Pokémon's confusion count](#berserk-genes-confusion-lasts-for-256-turns-or-the-previous-pokémons-confusion-count) - [Confusion damage is affected by type-boosting items and Explosion/Self-Destruct doubling](#confusion-damage-is-affected-by-type-boosting-items-and-explosionself-destruct-doubling) - [Moves that lower Defense can do so after breaking a Substitute](#moves-that-lower-defense-can-do-so-after-breaking-a-substitute) - [Counter and Mirror Coat still work if the opponent uses an item](#counter-and-mirror-coat-still-work-if-the-opponent-uses-an-item) - [A Disabled but PP Up–enhanced move may not trigger Struggle](#a-disabled-but-pp-upenhanced-move-may-not-trigger-struggle) - [A Pokémon that fainted from Pursuit will have its old status condition when revived](#a-pokémon-that-fainted-from-pursuit-will-have-its-old-status-condition-when-revived) - [Lock-On and Mind Reader don't always bypass Fly and Dig](#lock-on-and-mind-reader-dont-always-bypass-fly-and-dig) - [Beat Up can desynchronize link battles](#beat-up-can-desynchronize-link-battles) - [Beat Up works incorrectly with only one Pokémon in the party](#beat-up-works-incorrectly-with-only-one-pokémon-in-the-party) - [Beat Up may fail to raise Substitute](#beat-up-may-fail-to-raise-substitute) - [Beat Up may trigger King's Rock even if it failed](#beat-up-may-trigger-kings-rock-even-if-it-failed) - [Present damage is incorrect in link battles](#present-damage-is-incorrect-in-link-battles) - [Return and Frustration deal no damage when the user's happiness is low or high, respectively](#return-and-frustration-deal-no-damage-when-the-users-happiness-is-low-or-high-respectively) - [Dragon Scale, not Dragon Fang, boosts Dragon-type moves](#dragon-scale-not-dragon-fang-boosts-dragon-type-moves) - [Switching out or switching against a Pokémon with max HP below 4 freezes the game](#switching-out-or-switching-against-a-pokémon-with-max-HP-below-4-freezes-the-game) - [Moves that do damage and increase your stats do not increase stats after a KO](#moves-that-do-damage-and-increase-your-stats-do-not-increase-stats-after-a-ko) - [HP bar animation is slow for high HP](#hp-bar-animation-is-slow-for-high-hp) - [HP bar animation off-by-one error for low HP](#hp-bar-animation-off-by-one-error-for-low-hp) - [Single-player battle engine](#single-player-battle-engine) - [A Transformed Pokémon can use Sketch and learn otherwise unobtainable moves](#a-transformed-pokémon-can-use-sketch-and-learn-otherwise-unobtainable-moves) - [Catching a Transformed Pokémon always catches a Ditto](#catching-a-transformed-pokémon-always-catches-a-ditto) - [Experience underflow for level 1 Pokémon with Medium-Slow growth rate](#experience-underflow-for-level-1-pokémon-with-medium-slow-growth-rate) - [The Dude's catching tutorial may crash if his Poké Ball can't be used](#the-dudes-catching-tutorial-may-crash-if-his-poké-ball-cant-be-used) - [BRN/PSN/PAR do not affect catch rate](#brnpsnpar-do-not-affect-catch-rate) - [Moon Ball does not boost catch rate](#moon-ball-does-not-boost-catch-rate) - [Love Ball boosts catch rate for the wrong gender](#love-ball-boosts-catch-rate-for-the-wrong-gender) - [Fast Ball only boosts catch rate for three Pokémon](#fast-ball-only-boosts-catch-rate-for-three-pokémon) - [Heavy Ball uses wrong weight value for three Pokémon](#heavy-ball-uses-wrong-weight-value-for-three-pokémon) - [Glacier Badge may not boost Special Defense depending on the value of Special Attack](#glacier-badge-may-not-boost-special-defense-depending-on-the-value-of-special-attack) - ["Smart" AI encourages Mean Look if its own Pokémon is badly poisoned](#smart-ai-encourages-mean-look-if-its-own-pokémon-is-badly-poisoned) - ["Smart" AI discourages Conversion2 after the first turn](#smart-ai-discourages-conversion2-after-the-first-turn) - ["Smart" AI does not encourage Solar Beam, Flame Wheel, or Moonlight during Sunny Day](#smart-ai-does-not-encourage-solar-beam-flame-wheel-or-moonlight-during-sunny-day) - [AI does not discourage Future Sight when it's already been used](#ai-does-not-discourage-future-sight-when-its-already-been-used) - [AI makes a false assumption about `CheckTypeMatchup`](#ai-makes-a-false-assumption-about-checktypematchup) - [AI use of Full Heal or Full Restore does not cure Nightmare status](#ai-use-of-full-heal-or-full-restore-does-not-cure-nightmare-status) - [AI use of Full Heal does not cure confusion status](#ai-use-of-full-heal-does-not-cure-confusion-status) - [Wild Pokémon can always Teleport regardless of level difference](#wild-pokémon-can-always-teleport-regardless-of-level-difference) - [`RIVAL2` has lower DVs than `RIVAL1`](#rival2-has-lower-dvs-than-rival1) - [`HELD_CATCH_CHANCE` has no effect](#held_catch_chance-has-no-effect) - [Credits sequence changes move selection menu behavior](#credits-sequence-changes-move-selection-menu-behavior) - [Game engine](#game-engine) - [`LoadMetatiles` wraps around past 128 blocks](#loadmetatiles-wraps-around-past-128-blocks) - [Surfing directly across a map connection does not load the new map](#surfing-directly-across-a-map-connection-does-not-load-the-new-map) - [Swimming NPCs aren't limited by their movement radius](#swimming-npcs-arent-limited-by-their-movement-radius) - [Pokémon deposited in the Day-Care might lose experience](#pokémon-deposited-in-the-day-care-might-lose-experience) - [Graphics](#graphics) - [In-battle “`…`” ellipsis is too high](#in-battle--ellipsis-is-too-high) - [Two tiles in the `port` tileset are drawn incorrectly](#two-tiles-in-the-port-tileset-are-drawn-incorrectly) - [The Ruins of Alph research center's roof color at night looks wrong](#the-ruins-of-alph-research-centers-roof-color-at-night-looks-wrong) - [A hatching Unown egg would not show the right letter](#a-hatching-unown-egg-would-not-show-the-right-letter) - [Using a Park Ball in non-Contest battles has a corrupt animation](#using-a-park-ball-in-non-contest-battles-has-a-corrupt-animation) - [Battle transitions fail to account for the enemy's level](#battle-transitions-fail-to-account-for-the-enemys-level) - [Some trainer NPCs have inconsistent overworld sprites](#some-trainer-npcs-have-inconsistent-overworld-sprites) - [Audio](#audio) - [Slot machine payout sound effects cut each other off](#slot-machine-payout-sound-effects-cut-each-other-off) - [Team Rocket battle music is not used for Executives or Scientists](#team-rocket-battle-music-is-not-used-for-executives-or-scientists) - [No bump noise if standing on tile `$3E`](#no-bump-noise-if-standing-on-tile-3e) - [Playing Entei's Pokédex cry can distort Raikou's and Suicune's](#playing-enteis-pokédex-cry-can-distort-raikous-and-suicunes) - [Text](#text) - [Five-digit experience gain is printed incorrectly](#five-digit-experience-gain-is-printed-incorrectly) - [Only the first three evolution entries can have Stone compatibility reported correctly](#only-the-first-three-evolution-entries-can-have-stone-compatibility-reported-correctly) - [`EVOLVE_STAT` can break Stone compatibility reporting](#evolve_stat-can-break-stone-compatibility-reporting) - [A "HOF Master!" title for 200-Time Famers is defined but inaccessible](#a-hof-master-title-for-200-time-famers-is-defined-but-inaccessible) - [Scripted events](#scripted-events) - [Clair can give TM24 Dragonbreath twice](#clair-can-give-tm24-dragonbreath-twice) - [Daisy's grooming doesn't always increase happiness](#daisys-grooming-doesnt-always-increase-happiness) - [Magikarp in Lake of Rage are shorter, not longer](#magikarp-in-lake-of-rage-are-shorter-not-longer) - [Magikarp length limits have a unit conversion error](#magikarp-length-limits-have-a-unit-conversion-error) - [Magikarp lengths can be miscalculated](#magikarp-lengths-can-be-miscalculated) - [`CheckOwnMon` only checks the first five letters of OT names](#checkownmon-only-checks-the-first-five-letters-of-ot-names) - [`CheckOwnMonAnywhere` does not check the Day-Care](#checkownmonanywhere-does-not-check-the-day-care) - [The unused `phonecall` script command may crash](#the-unused-phonecall-script-command-may-crash) - [Internal engine routines](#internal-engine-routines) - [Saves corrupted by mid-save shutoff are not handled](#saves-corrupted-by-mid-save-shutoff-are-not-handled) - [`ScriptCall` can overflow `wScriptStack` and crash](#scriptcall-can-overflow-wscriptstack-and-crash) - [`LoadSpriteGFX` does not limit the capacity of `UsedSprites`](#loadspritegfx-does-not-limit-the-capacity-of-usedsprites) - [`ChooseWildEncounter` doesn't really validate the wild Pokémon species](#choosewildencounter-doesnt-really-validate-the-wild-pokémon-species) - [`TryObjectEvent` arbitrary code execution](#tryobjectevent-arbitrary-code-execution) - [`ReadObjectEvents` overflows into `wObjectMasks`](#readobjectevents-overflows-into-wobjectmasks) - [`ClearWRAM` only clears WRAM bank 1](#clearwram-only-clears-wram-bank-1) - [`BattleAnimCmd_ClearObjs` only clears the first 6⅔ objects](#battleanimcmd_clearobjs-only-clears-the-first-6-objects) ## Multi-player battle engine ### Perish Song and Spikes can leave a Pokémon with 0 HP and not faint ([Video](https://www.youtube.com/watch?v=1IiPWw5fMf8&t=85)) **Fix:** Edit `CheckFaint_PlayerThenEnemy` and `CheckFaint_EnemyThenPlayer` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff jp HandleEncore +HasAnyoneFainted: + call HasPlayerFainted + jp nz, HasEnemyFainted + ret + CheckFaint_PlayerThenEnemy: +.faint_loop + call .Function + ret c + call HasAnyoneFainted + ret nz + jr .faint_loop + +.Function: call HasPlayerFainted jr nz, .PlayerNotFainted call HandlePlayerMonFaint ... ``` ```diff CheckFaint_EnemyThenPlayer: +.faint_loop + call .Function + ret c + call HasAnyoneFainted + ret nz + jr .faint_loop + +.Function: call HasEnemyFainted jr nz, .EnemyNotFainted call HandleEnemyMonFaint ... ``` ### Thick Club and Light Ball can make (Special) Attack wrap around above 1024 ([Video](https://www.youtube.com/watch?v=rGqu3d3pdok&t=450)) **Fix:** Edit `SpeciesItemBoost` in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm) ```diff ; Double the stat sla l rl h + + ld a, HIGH(MAX_STAT_VALUE) + cp h + jr c, .cap + ret nz + ld a, LOW(MAX_STAT_VALUE) + cp l + ret nc + +.cap + ld hl, MAX_STAT_VALUE ret ``` ### Metal Powder can increase damage taken with boosted (Special) Defense ([Video](https://www.youtube.com/watch?v=rGqu3d3pdok&t=450)) **Fix:** Edit [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm): ```diff DittoMetalPowder: ... - ld a, c - srl a - add c - ld c, a - ret nc - - srl b - ld a, b - and a - jr nz, .done - inc b -.done - scf - rr c + ld h, b + ld l, c + srl b + rr c + add hl, bc + ld b, h + ld c, l + + ld a, HIGH(MAX_STAT_VALUE) + cp b + jr c, .cap + ret nz + ld a, LOW(MAX_STAT_VALUE) + cp c + ret nc + +.cap + ld bc, MAX_STAT_VALUE ret ``` ```diff PlayerAttackDamage: ... .done + push hl + call DittoMetalPowder + pop hl call TruncateHL_BC ld a, [wBattleMonLevel] ld e, a - call DittoMetalPowder ld a, 1 and a ret ``` ```diff EnemyAttackDamage: ... .done + push hl + call DittoMetalPowder + pop hl call TruncateHL_BC ld a, [wBattleMonLevel] ld e, a - call DittoMetalPowder ld a, 1 and a ret ``` ### Reflect and Light Screen can make (Special) Defense wrap around above 1024 This bug existed for all battles in Gold and Silver, and was only fixed for single-player battles in Crystal to preserve link compatibility. **Fix:** Edit `TruncateHL_BC` in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm) ```diff .finish - ld a, [wLinkMode] - cp LINK_COLOSSEUM - jr z, .done ; If we go back to the loop point, ; it's the same as doing this exact ; same check twice. ld a, h or b jr nz, .loop -.done ld b, l ret ``` (This fix also affects Thick Club, Light Ball, and Metal Powder, as described above, but their specific fixes in the above bugs allow more accurate damage calculations.) ### Moves with a 100% secondary effect chance will not trigger it in 1/256 uses ([Video](https://www.youtube.com/watch?v=mHkyO5T5wZU&t=206)) **Fix:** Edit `BattleCommand_EffectChance` in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm): ```diff - ; BUG: 1/256 chance to fail even for a 100% effect chance, - ; since carry is not set if BattleRandom == [hl] == 255 - call BattleRandom + ld a, [hl] + sub 100 percent + ; If chance was 100%, RNG won't be called (carry not set) + ; Thus chance will be subtracted from 0, guaranteeing a carry + call c, BattleRandom cp [hl] pop hl ret c .failed ld a, 1 ld [wEffectFailed], a and a ret ``` **Compatibility preservation:** If you wish to keep compatibility with standard Pokémon Crystal, you can disable the fix during link battles by also applying the following edit in the same place: ```diff + ld a, [wLinkMode] + cp LINK_COLOSSEUM + scf ; Force RNG to be called + jr z, .nofix ; Don't apply fix in link battles, for compatibility ld a, [hl] sub 100 percent ; If chance was 100%, RNG won't be called (carry not set) ; Thus chance will be subtracted from 0, guaranteeing a carry +.nofix call c, BattleRandom ``` ### Belly Drum sharply boosts Attack even with under 50% HP ([Video](https://www.youtube.com/watch?v=zuCLMikWo4Y)) **Fix:** Edit `BattleCommand_BellyDrum` in [engine/battle/move_effects/belly_drum.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/belly_drum.asm): ```diff BattleCommand_BellyDrum: ; bellydrum -; This command is buggy because it raises the user's attack -; before checking that it has enough HP to use the move. -; Swap the order of these two blocks to fix. - call BattleCommand_AttackUp2 - ld a, [wAttackMissed] - and a - jr nz, .failed - callfar GetHalfMaxHP callfar CheckUserHasEnoughHP jr nc, .failed + + push bc + call BattleCommand_AttackUp2 + pop bc + ld a, [wAttackMissed] + and a + jr nz, .failed ``` ### Berserk Gene's confusion lasts for 256 turns or the previous Pokémon's confusion count ([Video](https://youtube.com/watch?v=Pru3mohq20A)) **Fix:** Edit `HandleBerserkGene` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff HandleBerserkGene: ... ld a, BATTLE_VARS_SUBSTATUS3 call GetBattleVarAddr push af set SUBSTATUS_CONFUSED, [hl] + ldh a, [hBattleTurn] + and a + ld hl, wPlayerConfuseCount + jr z, .set_confuse_count + ld hl, wEnemyConfuseCount +.set_confuse_count + call BattleRandom + and %11 + add 2 + ld [hl], a ld a, BATTLE_VARS_MOVE_ANIM call GetBattleVarAddr ... ``` This makes the Berserk Gene use the regular confusion duration (2–5 turns). ### Confusion damage is affected by type-boosting items and Explosion/Self-Destruct doubling ([Video](https://twitter.com/crystal_rby/status/874626362287562752)) **Fix:** First, edit [wram.asm](https://github.com/pret/pokecrystal/blob/master/wram.asm): ```diff wTurnEnded:: db - ds 1 +wIsConfusionDamage:: db wPlayerStats:: ``` Then edit four routines in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm): ```diff HitSelfInConfusion: ... call TruncateHL_BC ld d, 40 pop af ld e, a + ld a, TRUE + ld [wIsConfusionDamage], a ret ``` ```diff BattleCommand_DamageCalc: ; damagecalc ... .skip_zero_damage_check + xor a ; Not confusion damage + ld [wIsConfusionDamage], a + ; fallthrough + +ConfusionDamageCalc: ; Minimum defense value is 1. ld a, c and a jr nz, .not_dividing_by_zero ld c, 1 .not_dividing_by_zero ... ; Item boosts + +; Item boosts don't apply to confusion damage + ld a, [wIsConfusionDamage] + and a + jr nz, .DoneItem + call GetUserItem ... ``` ```diff CheckEnemyTurn: ... ld hl, HurtItselfText call StdBattleTextbox call HitSelfInConfusion - call BattleCommand_DamageCalc + call ConfusionDamageCalc call BattleCommand_LowerSub ... ``` ```diff HitConfusion: ld hl, HurtItselfText call StdBattleTextbox xor a ld [wCriticalHit], a call HitSelfInConfusion - call BattleCommand_DamageCalc + call ConfusionDamageCalc call BattleCommand_LowerSub ``` ### Moves that lower Defense can do so after breaking a Substitute ([Video](https://www.youtube.com/watch?v=OGwKPRJLaaI)) This bug affects Acid, Iron Tail, and Rock Smash. **Fix:** Edit `DefenseDownHit` in [data/moves/effects.asm](https://github.com/pret/pokecrystal/blob/master/data/moves/effects.asm): ```diff DefenseDownHit: checkobedience usedmovetext doturn critical damagestats damagecalc stab damagevariation checkhit effectchance hittarget failuretext checkfaint criticaltext supereffectivetext checkfaint buildopponentrage - effectchance ; bug: duplicate effectchance shouldn't be here defensedown statdownmessage endmove ``` ### Counter and Mirror Coat still work if the opponent uses an item ([Video](https://www.youtube.com/watch?v=uRYyzKRatFk)) **Fix:** Edit `BattleCommand_Counter` in [engine/battle/move_effects/counter.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/counter.asm) and `BattleCommand_MirrorCoat` in [engine/battle/move_effects/mirror_coat.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/mirror_coat.asm): ```diff - ; BUG: Move should fail with all non-damaging battle actions ld hl, wCurDamage ld a, [hli] or [hl] - ret z + jr z, .failed ``` Add this to the end of each file: ```diff +.failed + ld a, 1 + ld [wEffectFailed], a + and a + ret ``` ### A Disabled but PP Up–enhanced move may not trigger Struggle ([Video](https://www.youtube.com/watch?v=1v9x4SgMggs)) **Fix:** Edit `CheckPlayerHasUsableMoves` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff .done - ; Bug: this will result in a move with PP Up confusing the game. - and a ; should be "and PP_MASK" + and PP_MASK ret nz .force_struggle ld hl, BattleText_MonHasNoMovesLeft call StdBattleTextbox ld c, 60 call DelayFrames xor a ret ``` ### A Pokémon that fainted from Pursuit will have its old status condition when revived ([Video](https://www.youtube.com/watch?v=tiRvw-Nb2ME)) **Fix:** Edit `PursuitSwitch` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm) ```diff ld a, $f0 ld [wCryTracks], a ld a, [wBattleMonSpecies] call PlayStereoCry + ld a, [wCurBattleMon] + push af ld a, [wLastPlayerMon] + ld [wCurBattleMon], a + call UpdateFaintedPlayerMon + pop af + ld [wCurBattleMon], a - ld c, a - ld hl, wBattleParticipantsNotFainted - ld b, RESET_FLAG - predef SmallFarFlagAction call PlayerMonFaintedAnimation ld hl, BattleText_MonFainted jr .done_fainted ``` ### Lock-On and Mind Reader don't always bypass Fly and Dig This bug affects Attract, Curse, Foresight, Mean Look, Mimic, Nightmare, Spider Web, Transform, and stat-lowering effects of moves like String Shot or Bubble during the semi-invulnerable turn of Fly or Dig. **Fix:** Edit `CheckHiddenOpponent` in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm): ```diff CheckHiddenOpponent: -; BUG: This routine is completely redundant and introduces a bug, since BattleCommand_CheckHit does these checks properly. - ld a, BATTLE_VARS_SUBSTATUS3_OPP - call GetBattleVar - and 1 << SUBSTATUS_FLYING | 1 << SUBSTATUS_UNDERGROUND + xor a ret ``` ### Beat Up can desynchronize link battles ([Video](https://www.youtube.com/watch?v=202-iAsrIa8)) **Fix:** Edit `BattleCommand_BeatUp` in [engine/battle/move_effects/beat_up.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/beat_up.asm): ```diff .got_mon ld a, [wCurBeatUpPartyMon] ld hl, wPartyMonNicknames call GetNickname ld a, MON_HP call GetBeatupMonLocation ld a, [hli] or [hl] jp z, .beatup_fail ; fainted ld a, [wCurBeatUpPartyMon] ld c, a ld a, [wCurBattleMon] - ; BUG: this can desynchronize link battles - ; Change "cp [hl]" to "cp c" to fix - cp [hl] + cp c ld hl, wBattleMonStatus jr z, .active_mon ld a, MON_STATUS call GetBeatupMonLocation .active_mon ld a, [hl] and a jp nz, .beatup_fail ``` ### Beat Up works incorrectly with only one Pokémon in the party This bug prevents the rest of Beat Up's effect from being executed if the player or enemy only has one Pokémon in their party while using it. It prevents Substitute from being raised and King's Rock from working. **Fix:** Edit `BattleCommand_EndLoop` in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm): ```diff .only_one_beatup ld a, BATTLE_VARS_SUBSTATUS3 call GetBattleVarAddr res SUBSTATUS_IN_LOOP, [hl] - call BattleCommand_BeatUpFailText - jp EndMoveEffect + ret ``` **Cosmetic fix:** This fix does not break compatibility, but it only affects what's shown on the screen for the patched game. ```diff .only_one_beatup ld a, BATTLE_VARS_SUBSTATUS3 call GetBattleVarAddr res SUBSTATUS_IN_LOOP, [hl] call BattleCommand_BeatUpFailText + call BattleCommand_RaiseSub jp EndMoveEffect ``` ### Beat Up may fail to raise Substitute *Fixing this cosmetic bug will* not *break link battle compatibility.* This bug prevents Substitute from being raised if Beat Up was blocked by Protect or Detect. **Fix:** Edit `BattleCommand_FailureText` in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm). ```diff cp EFFECT_MULTI_HIT jr z, .multihit cp EFFECT_DOUBLE_HIT jr z, .multihit cp EFFECT_POISON_MULTI_HIT jr z, .multihit + cp EFFECT_BEAT_UP + jr z, .multihit jp EndMoveEffect .multihit call BattleCommand_RaiseSub jp EndMoveEffect ``` ### Beat Up may trigger King's Rock even if it failed This bug is caused because Beat Up never sets `wAttackMissed`, even when no Pokémon was able to attack (due to being fainted or having a status condition). **Fix:** Edit `BattleCommand_BeatUpFailText` in [engine/battle/move_effects/beat_up.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/beat_up.asm): ```diff BattleCommand_BeatUpFailText: ; beatupfailtext ld a, [wBeatUpHitAtLeastOnce] and a ret nz + + inc a + ld [wAttackMissed], a jp PrintButItFailed ``` ### Present damage is incorrect in link battles ([Video](https://www.youtube.com/watch?v=XJaQoKtrEuw)) This bug existed for all battles in Gold and Silver, and was only fixed for single-player battles in Crystal to preserve link compatibility. **Fix:** Edit `BattleCommand_Present` in [engine/battle/move_effects/present.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/present.asm): ```diff BattleCommand_Present: ; present - ld a, [wLinkMode] - cp LINK_COLOSSEUM - jr z, .colosseum_skippush push bc push de -.colosseum_skippush - call BattleCommand_Stab - - ld a, [wLinkMode] - cp LINK_COLOSSEUM - jr z, .colosseum_skippop pop de pop bc -.colosseum_skippop ``` ### Return and Frustration deal no damage when the user's happiness is low or high, respectively This happens because the user's happiness (or 255 − happiness for Frustration) is multiplied by 10 and divided by 25, which rounds down to zero when the happiness is 0–2 (or 253–255 for Frustration). **Fix:** Edit [engine/battle/move_effects/return.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/return.asm): ```diff BattleCommand_HappinessPower: ... call Multiply ld a, 25 ldh [hDivisor], a ld b, 4 call Divide ldh a, [hQuotient + 3] + and a + jr nz, .done + inc a +.done ld d, a pop bc ret ``` And edit [engine/battle/move_effects/frustration.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/frustration.asm): ```diff BattleCommand_FrustrationPower: ... call Multiply ld a, 25 ldh [hDivisor], a ld b, 4 call Divide ldh a, [hQuotient + 3] + and a + jr nz, .done + inc a +.done ld d, a pop bc ret ``` ### Dragon Scale, not Dragon Fang, boosts Dragon-type moves **Fix:** Edit `ItemAttributes` in [data/items/attributes.asm](https://github.com/pret/pokecrystal/blob/master/data/items/attributes.asm): ```diff ; DRAGON_FANG - item_attribute 100, HELD_NONE, 0, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE + item_attribute 100, HELD_DRAGON_BOOST, 10, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE ... ; DRAGON_SCALE - item_attribute 2100, HELD_DRAGON_BOOST, 10, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE + item_attribute 2100, HELD_NONE, 0, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE ``` ### Switching out or switching against a Pokémon with max HP below 4 freezes the game This happens because switching involves calculating a percentage of maximum enemy HP. Directly calculating *HP* × 100 / *max HP* would require a two-byte denominator, so instead the game calculates *HP* × 25 / (*max HP* / 4), since even a maximum HP of 999 divided by 4 is 249, which fits in one byte. However, if the maximum HP is below 4 this will divide by 0, which enters an infinite loop in `_Divide`. **Fix:** First, edit `SendOutMonText` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff ; compute enemy health remaining as a percentage xor a ldh [hMultiplicand + 0], a ld hl, wEnemyMonHP ld a, [hli] ld [wEnemyHPAtTimeOfPlayerSwitch], a ldh [hMultiplicand + 1], a ld a, [hl] ld [wEnemyHPAtTimeOfPlayerSwitch + 1], a ldh [hMultiplicand + 2], a - ld a, 25 - ldh [hMultiplier], a - call Multiply ld hl, wEnemyMonMaxHP ld a, [hli] ld b, [hl] - srl a - rr b - srl a - rr b + ld c, 100 + and a + jr z, .shift_done +.shift + rra + rr b + srl c + and a + jr nz, .shift +.shift_done + ld a, c + ldh [hMultiplier], a + call Multiply ld a, b ld b, 4 ldh [hDivisor], a call Divide ``` Then edit `WithdrawMonText` in the same file: ```diff ; compute enemy health lost as a percentage ld hl, wEnemyMonHP + 1 ld de, wEnemyHPAtTimeOfPlayerSwitch + 1 ld b, [hl] dec hl ld a, [de] sub b ldh [hMultiplicand + 2], a dec de ld b, [hl] ld a, [de] sbc b ldh [hMultiplicand + 1], a - ld a, 25 - ldh [hMultiplier], a - call Multiply ld hl, wEnemyMonMaxHP ld a, [hli] ld b, [hl] - srl a - rr b - srl a - rr b + ld c, 100 + and a + jr z, .shift_done +.shift + rra + rr b + srl c + and a + jr nz, .shift +.shift_done + ld a, c + ldh [hMultiplier], a + call Multiply ld a, b ld b, 4 ldh [hDivisor], a call Divide ``` This changes both calculations to *HP* × (100 / *N*) / (*max HP* / *N*) for the smallest necessary *N*, which will be at least 1, so it avoids dividing by zero and is also more accurate. ### Moves that do damage and increase your stats do not increase stats after a KO `BattleCommand_CheckFaint` "ends the move effect if the opponent faints", and these moves attempt to raise the user's stats *after* `checkfaint`. Note that fixing this can lead to stats being increased at the end of battle, but will not have any negative effects. **Fix:** Edit [data/moves/effects.asm](https://github.com/pret/pokecrystal/blob/master/data/moves/effects.asm): ```diff DefenseUpHit: ... criticaltext supereffectivetext + defenseup + statupmessage checkfaint buildopponentrage - defenseup - statupmessage endmove AttackUpHit: ... criticaltext supereffectivetext + attackup + statupmessage checkfaint buildopponentrage - attackup - statupmessage endmove AllUpHit: ... criticaltext supereffectivetext + allstatsup checkfaint buildopponentrage - allstatsup endmove ``` ### HP bar animation is slow for high HP *Fixing this cosmetic bug will* not *break link battle compatibility.* ([Video](https://www.youtube.com/watch?v=SE-BfsFgZVM)) **Fix:** Edit `LongAnim_UpdateVariables` in [engine/battle/anim_hp_bar.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/anim_hp_bar.asm): ```diff - ; This routine is buggy. The result from ComputeHPBarPixels is stored - ; in e. However, the pop de opcode deletes this result before it is even - ; used. The game then proceeds as though it never deleted that output. - ; To fix, uncomment the line below. call ComputeHPBarPixels - ; ld a, e + ld a, e pop bc pop de pop hl - ld a, e ; Comment or delete this line to fix the above bug. ld hl, wCurHPBarPixels cp [hl] jr z, .loop ld [hl], a and a ret ``` ### HP bar animation off-by-one error for low HP *Fixing this cosmetic bug will* not *break link battle compatibility.* ([Video](https://www.youtube.com/watch?v=9KyNVIZxJvI)) **Fix:** Edit `ShortHPBar_CalcPixelFrame` in [engine/battle/anim_hp_bar.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/anim_hp_bar.asm): ```diff ld b, 0 -; This routine is buggy. If [wCurHPAnimMaxHP] * [wCurHPBarPixels] is -; divisible by HP_BAR_LENGTH_PX, the loop runs one extra time. -; To fix, uncomment the line below. .loop ld a, l sub HP_BAR_LENGTH_PX ld l, a ld a, h sbc $0 ld h, a - ; jr z, .done + jr z, .done jr c, .done inc b jr .loop ``` ## Single-player battle engine ### A Transformed Pokémon can use Sketch and learn otherwise unobtainable moves ([Video](https://www.youtube.com/watch?v=AFiBxAOkCGI)) **Fix:** Edit `BattleCommand_Sketch` in [engine/battle/move_effects/sketch.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/sketch.asm): ```diff -; If the opponent is transformed, fail. +; If the user is transformed, fail. - ld a, BATTLE_VARS_SUBSTATUS5_OPP + ld a, BATTLE_VARS_SUBSTATUS5 call GetBattleVarAddr bit SUBSTATUS_TRANSFORMED, [hl] jp nz, .fail ``` ### Catching a Transformed Pokémon always catches a Ditto This bug can affect Mew or Pokémon other than Ditto that used Transform via Mirror Move or Sketch. **Fix:** Edit `PokeBallEffect` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff ld hl, wEnemySubStatus5 ld a, [hl] push af set SUBSTATUS_TRANSFORMED, [hl] -; This code is buggy. Any wild Pokémon that has Transformed will be -; caught as a Ditto, even if it was something else like Mew. -; To fix, do not set [wTempEnemyMonSpecies] to DITTO. bit SUBSTATUS_TRANSFORMED, a - jr nz, .ditto - jr .not_ditto + jr nz, .load_data -.ditto - ld a, DITTO - ld [wTempEnemyMonSpecies], a - jr .load_data - -.not_ditto - set SUBSTATUS_TRANSFORMED, [hl] ld hl, wEnemyBackupDVs ld a, [wEnemyMonDVs] ld [hli], a ld a, [wEnemyMonDVs + 1] ld [hl], a .load_data ld a, [wTempEnemyMonSpecies] ld [wCurPartySpecies], a ld a, [wEnemyMonLevel] ld [wCurPartyLevel], a farcall LoadEnemyMon pop af ld [wEnemySubStatus5], a ``` ### Experience underflow for level 1 Pokémon with Medium-Slow growth rate ([Video](https://www.youtube.com/watch?v=SXH8u0plHrE)) This can bring Pokémon straight from level 1 to 100 by gaining just a few experience points. **Fix:** Edit `CalcExpAtLevel` in [engine/pokemon/experience.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokemon/experience.asm): ```diff CalcExpAtLevel: ; (a/b)*n**3 + c*n**2 + d*n - e + ld a, d + dec a + jr nz, .UseExpFormula +; Pokémon have 0 experience at level 1 + ld hl, hProduct + ld [hli], a + ld [hli], a + ld [hli], a + ld [hl], a + ret + +.UseExpFormula ld a, [wBaseGrowthRate] add a add a ld c, a ld b, 0 ld hl, GrowthRates add hl, bc ``` ### The Dude's catching tutorial may crash if his Poké Ball can't be used ([Video](https://www.youtube.com/watch?v=A8zaTOkjKS4&t=407)) This can occur if your party and current PC box are both full when you start the tutorial. **Fix:** Edit `PokeBallEffect` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff ld a, [wBattleMode] dec a jp nz, UseBallInTrainerBattle + ld a, [wBattleType] + cp BATTLETYPE_TUTORIAL + jr z, .room_in_party + ld a, [wPartyCount] cp PARTY_LENGTH jr nz, .room_in_party ld a, BANK(sBoxCount) call OpenSRAM ld a, [sBoxCount] cp MONS_PER_BOX call CloseSRAM jp z, Ball_BoxIsFullMessage ``` ### BRN/PSN/PAR do not affect catch rate **Fix:** Edit `PokeBallEffect` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff -; This routine is buggy. It was intended that SLP and FRZ provide a higher -; catch rate than BRN/PSN/PAR, which in turn provide a higher catch rate than -; no status effect at all. But instead, it makes BRN/PSN/PAR provide no -; benefit. -; Uncomment the line below to fix this. ld b, a ld a, [wEnemyMonStatus] and 1 << FRZ | SLP ld c, 10 jr nz, .addstatus - ; ld a, [wEnemyMonStatus] + ld a, [wEnemyMonStatus] and a ld c, 5 jr nz, .addstatus ld c, 0 .addstatus ld a, b add c jr nc, .max_1 ld a, $ff .max_1 ``` ### Moon Ball does not boost catch rate **Fix:** Edit `MoonBallMultiplier` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff -; Moon Stone's constant from Pokémon Red is used. -; No Pokémon evolve with Burn Heal, -; so Moon Balls always have a catch rate of 1×. push bc ld a, BANK("Evolutions and Attacks") call GetFarByte - cp MOON_STONE_RED ; BURN_HEAL + cp MOON_STONE pop bc ret nz ``` ### Love Ball boosts catch rate for the wrong gender **Fix:** Edit `LoveBallMultiplier` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff .wildmale ld a, d pop de cp d pop bc - ret nz ; for the intended effect, this should be "ret z" + ret z ``` ### Fast Ball only boosts catch rate for three Pokémon **Fix:** Edit `FastBallMultiplier` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff .loop ld a, BANK(FleeMons) call GetFarByte inc hl cp -1 jr z, .next cp c - jr nz, .next ; for the intended effect, this should be "jr nz, .loop" + jr nz, .loop sla b jr c, .max ``` ### Heavy Ball uses wrong weight value for three Pokémon **Fix:** Edit `HeavyBall_GetDexEntryBank` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff HeavyBall_GetDexEntryBank: -; This function is buggy. -; It gets the wrong bank for Kadabra (64), Tauros (128), and Sunflora (192). -; Uncomment the line below to fix this. push hl push de ld a, [wEnemyMonSpecies] - ; dec a + dec a rlca rlca maskbits NUM_DEX_ENTRY_BANKS ld hl, .PokedexEntryBanks ld d, 0 ld e, a add hl, de ld a, [hl] pop de pop hl ret .PokedexEntryBanks: db BANK("Pokedex Entries 001-064") db BANK("Pokedex Entries 065-128") db BANK("Pokedex Entries 129-192") db BANK("Pokedex Entries 193-251") ``` ### Glacier Badge may not boost Special Defense depending on the value of Special Attack As Pryce's dialog ("That BADGE will raise the SPECIAL stats of POKéMON.") implies, Glacier Badge is intended to boost both Special Attack and Special Defense. However, due to BoostStat overwriting `a` when boosting Special Attack, the Special Defense boost will not happen if the unboosted Special Attack stat is either 0–205 or 433–660. **Fix:** Edit `BadgeStatBoosts.CheckBadge` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff .CheckBadge: ld a, b srl b + push af call c, BoostStat + pop af inc hl inc hl ; Check every other badge. srl b dec c jr nz, .CheckBadge ; Check GlacierBadge again for Special Defense. -; This check is buggy because it assumes that a is set by the "ld a, b" in the above loop, -; but it can actually be overwritten by the call to BoostStat. srl a call c, BoostStat ret ``` ### "Smart" AI encourages Mean Look if its own Pokémon is badly poisoned ([Video](https://www.youtube.com/watch?v=cygMO-zHTls)) **Fix:** Edit `AI_Smart_MeanLook` in [engine/battle/ai/scoring.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/ai/scoring.asm): ```diff -; 80% chance to greatly encourage this move if the enemy is badly poisoned (buggy). -; Should check wPlayerSubStatus5 instead. - ld a, [wEnemySubStatus5] +; 80% chance to greatly encourage this move if the player is badly poisoned + ld a, [wPlayerSubStatus5] bit SUBSTATUS_TOXIC, a jr nz, .asm_38e26 ``` ### "Smart" AI discourages Conversion2 after the first turn **Fix:** Edit `AI_Smart_Conversion2` in [engine/battle/ai/scoring.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/ai/scoring.asm): ```diff AI_Smart_Conversion2: ld a, [wLastPlayerMove] and a - jr nz, .discourage ; should be jr z + jr z, .discourage ``` ### "Smart" AI does not encourage Solar Beam, Flame Wheel, or Moonlight during Sunny Day **Fix:** Edit `SunnyDayMoves` in [data/battle/ai/sunny_day_moves.asm](https://github.com/pret/pokecrystal/blob/master/data/battle/ai/sunny_day_moves.asm): ```diff SunnyDayMoves: db FIRE_PUNCH db EMBER db FLAMETHROWER + db SOLARBEAM db FIRE_SPIN db FIRE_BLAST + db FLAME_WHEEL db SACRED_FIRE db MORNING_SUN db SYNTHESIS + db MOONLIGHT db -1 ; end ``` ### AI does not discourage Future Sight when it's already been used **Fix:** Edit `AI_Redundant` in [engine/battle/ai/redundant.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/ai/redundant.asm): ```diff .FutureSight: - ld a, [wEnemyScreens] - bit 5, a + ld a, [wEnemyFutureSightCount] + and a ret ``` ### AI makes a false assumption about `CheckTypeMatchup` **Fix:** Edit `BattleCheckTypeMatchup` in [engine/battle/effect_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/effect_commands.asm): ```diff BattleCheckTypeMatchup: ld hl, wEnemyMonType1 ldh a, [hBattleTurn] and a - jr z, CheckTypeMatchup + jr z, .get_type ld hl, wBattleMonType1 +.get_type + ld a, BATTLE_VARS_MOVE_TYPE + call GetBattleVar ; preserves hl, de, and bc CheckTypeMatchup: -; There is an incorrect assumption about this function made in the AI related code: when -; the AI calls CheckTypeMatchup (not BattleCheckTypeMatchup), it assumes that placing the -; offensive type in a will make this function do the right thing. Since a is overwritten, -; this assumption is incorrect. A simple fix would be to load the move type for the -; current move into a in BattleCheckTypeMatchup, before falling through, which is -; consistent with how the rest of the code assumes this code works like. push hl push de push bc - ld a, BATTLE_VARS_MOVE_TYPE - call GetBattleVar ld d, a ... ``` ### AI use of Full Heal or Full Restore does not cure Nightmare status ([Video](https://www.youtube.com/watch?v=rGqu3d3pdok&t=322)) **Fix:** Edit `AI_HealStatus` in [engine/battle/ai/items.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/ai/items.asm): ```diff AI_HealStatus: ld a, [wCurOTMon] ld hl, wOTPartyMon1Status ld bc, PARTYMON_STRUCT_LENGTH call AddNTimes xor a ld [hl], a ld [wEnemyMonStatus], a - ; Bug: this should reset SUBSTATUS_NIGHTMARE - ; Uncomment the 2 lines below to fix - ; ld hl, wEnemySubStatus1 - ; res SUBSTATUS_NIGHTMARE, [hl] + ld hl, wEnemySubStatus1 + res SUBSTATUS_NIGHTMARE, [hl] ... ``` ### AI use of Full Heal does not cure confusion status **Fix:** Edit `EnemyUsedFullRestore`, and `AI_HealStatus` in [engine/battle/ai/items.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/ai/items.asm): ```diff EnemyUsedFullRestore: call AI_HealStatus ld a, FULL_RESTORE ld [wCurEnemyItem], a - ld hl, wEnemySubStatus3 - res SUBSTATUS_CONFUSED, [hl] - xor a - ld [wEnemyConfuseCount], a ``` ```diff AI_HealStatus: ld a, [wCurOTMon] ld hl, wOTPartyMon1Status ld bc, PARTYMON_STRUCT_LENGTH call AddNTimes xor a ld [hl], a ld [wEnemyMonStatus], a + ld [wEnemyConfuseCount], a ; Bug: this should reset SUBSTATUS_NIGHTMARE ; Uncomment the 2 lines below to fix ; ld hl, wEnemySubStatus1 ; res SUBSTATUS_NIGHTMARE, [hl] - ; Bug: this should reset SUBSTATUS_CONFUSED - ; Uncomment the 2 lines below to fix - ; ld hl, wEnemySubStatus3 - ; res SUBSTATUS_CONFUSED, [hl] + ld hl, wEnemySubStatus3 + res SUBSTATUS_CONFUSED, [hl] ld hl, wEnemySubStatus5 res SUBSTATUS_TOXIC, [hl] ret ``` ### Wild Pokémon can always Teleport regardless of level difference **Fix:** Edit `BattleCommand_Teleport` in [engine/battle/move_effects/teleport.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/move_effects/teleport.asm): ```diff .loop_enemy call BattleRandom cp c jr nc, .loop_enemy ; b = player level / 4 srl b srl b - ; This should be "jr c, .failed" - ; As written, it makes enemy use of Teleport always succeed if able + ; If the random number >= player level / 4, Teleport will succeed cp b - jr nc, .run_away + jr c, .failed ``` ### `RIVAL2` has lower DVs than `RIVAL1` `RIVAL1` is battled throughout the game. `RIVAL2` is battled at Indigo Plateau, and would not be expected to have worse DVs. **Fix:** Edit `TrainerClassDVs` in [data/trainers/dvs.asm](https://github.com/pret/pokecrystal/blob/master/data/trainers/dvs.asm): ```diff dn 13, 13, 13, 13 ; RIVAL1 ... - dn 9, 8, 8, 8 ; RIVAL2 + dn 13, 13, 13, 13 ; RIVAL2 ``` ### `HELD_CATCH_CHANCE` has no effect **Fix:** Edit `PokeBallEffect` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff - ; BUG: farcall overwrites a, and GetItemHeldEffect takes b anyway. - ; This is probably the reason the HELD_CATCH_CHANCE effect is never used. - ; Uncomment the line below to fix. ld d, a push de ld a, [wBattleMonItem] - ; ld b, a + ld b, a farcall GetItemHeldEffect ld a, b cp HELD_CATCH_CHANCE pop de ld a, d jr nz, .max_2 add c jr nc, .max_2 ld a, $ff .max_2 ``` ### Credits sequence changes move selection menu behavior ([Video](https://www.youtube.com/watch?v=vjFUo6Jr4po&t=438)) To select a move in battle, you have to press and release the Up or Down buttons. However, after playing the credits sequence, holding down either button will continuously scroll through the moves. **Fix:** Edit `Credits` in [engine/movie/credits.asm](https://github.com/pret/pokecrystal/blob/master/engine/movie/credits.asm): ```diff ldh a, [hVBlank] push af ld a, $5 ldh [hVBlank], a + ldh a, [hInMenu] + push af ld a, $1 ldh [hInMenu], a ... ldh [hLCDCPointer], a ldh [hBGMapAddress], a + pop af + ldh [hInMenu], a pop af ldh [hVBlank], a pop af ldh [rSVBK], a ``` The `[hInMenu]` value determines this button behavior. However, the battle moves menu doesn't actually set `[hInMenu]` to anything, so either behavior *may* have been intentional. The default 0 prevents continuous scrolling; a value of 1 allows it. (The Japanese release sets it to 0.) **Optional fix:** To explicitly set a `[hInMenu]` for the moves menu, edit `BattleTurn` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff BattleTurn: + ldh a, [hInMenu] + push af + ld a, 1 ; or "xor a" for the value 0 + ldh [hInMenu], a + .loop ... jp .loop .quit + pop af + ldh [hInMenu], a ret ``` ## Game engine ### `LoadMetatiles` wraps around past 128 blocks This bug prevents you from using blocksets with more than 128 blocks. **Fix:** Edit `LoadMetatiles` in [home/map.asm](https://github.com/pret/pokecrystal/blob/master/home/map.asm): ```diff ; Set hl to the address of the current metatile data ([wTilesetBlocksAddress] + (a) tiles). - ; This is buggy; it wraps around past 128 blocks. - ; To fix, uncomment the line below. - add a ; Comment or delete this line to fix the above bug. ld l, a ld h, 0 - ; add hl, hl + add hl, hl add hl, hl add hl, hl add hl, hl ld a, [wTilesetBlocksAddress] add l ld l, a ld a, [wTilesetBlocksAddress + 1] adc h ld h, a ``` ### Surfing directly across a map connection does not load the new map ([Video](https://www.youtube.com/watch?v=XFOWvMNG-zw)) **Fix:** First, edit `UsedSurfScript` in [engine/events/overworld.asm](https://github.com/pret/pokecrystal/blob/master/engine/events/overworld.asm): ```diff UsedSurfScript: writetext UsedSurfText ; "used SURF!" waitbutton closetext callasm .empty_fn ; empty function readmem wSurfingPlayerState writevar VAR_MOVEMENT special UpdatePlayerSprite special PlayMapMusic -; step into the water (slow_step DIR, step_end) special SurfStartStep - applymovement PLAYER, wMovementBuffer end ``` Then edit `SurfStartStep` in [engine/overworld/player_object.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/player_object.asm): ```diff SurfStartStep: - call InitMovementBuffer - call .GetMovementData - call AppendToMovementBuffer - ld a, movement_step_end - call AppendToMovementBuffer - ret - -.GetMovementData: ld a, [wPlayerDirection] srl a srl a maskbits NUM_DIRECTIONS ld e, a ld d, 0 ld hl, .movement_data add hl, de - ld a, [hl] - ret + add hl, de + add hl, de + ld a, BANK(.movement_data) + jp StartAutoInput .movement_data - slow_step DOWN - slow_step UP - slow_step LEFT - slow_step RIGHT + db D_DOWN, 0, -1 + db D_UP, 0, -1 + db D_LEFT, 0, -1 + db D_RIGHT, 0, -1 ``` This fix will make the player enter the water at a normal walking speed, not with a slow step. ### Swimming NPCs aren't limited by their movement radius This bug is why the Lapras in [maps/UnionCaveB2F.asm](https://github.com/pret/pokecrystal/blob/master/maps/UnionCaveB2F.asm), which uses `SPRITEMOVEDATA_SWIM_WANDER`, is not restricted by its `1, 1` movement radius. **Fix:** Edit `CanObjectMoveInDirection` in [engine/overworld/npc_movement.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/npc_movement.asm): ```diff ld hl, OBJECT_FLAGS1 add hl, bc bit NOCLIP_TILES_F, [hl] ; lost, uncomment next line to fix - ; jr nz, .noclip_tiles + jr nz, .noclip_tiles ``` ### Pokémon deposited in the Day-Care might lose experience This happens because when a Pokémon is withdrawn from the Day-Care, its Exp. Points are reset to the minimum required for its level. This means that if it hasn't gained any levels, it may lose experience. **Fix**: Edit `RetrieveBreedmon` in [engine/pokemon/move_mon.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokemon/move_mon.asm): ```diff RetrieveBreedmon: ... ld a, [wPartyCount] dec a ld [wCurPartyMon], a farcall HealPartyMon - ld a, [wCurPartyLevel] - ld d, a + ; Check if there's an exp overflow + ld d, MAX_LEVEL callfar CalcExpAtLevel pop bc - ld hl, MON_EXP + ld hl, MON_EXP + 2 add hl, bc ldh a, [hMultiplicand] - ld [hli], a + ld b, a ldh a, [hMultiplicand + 1] - ld [hli], a + ld c, a ldh a, [hMultiplicand + 2] + ld d, a + ld a, [hld] + sub d + ld a, [hld] + sbc c + ld a, [hl] + sbc b + jr c, .not_max_exp + ld a, b + ld [hli], a + ld a, c + ld [hli], a + ld a, d ld [hl], a +.not_max_exp and a ret ``` ## Graphics ### In-battle “`…`” ellipsis is too high This is a mistake with the “`…`” tile in [gfx/battle/hp_exp_bar_border.png](https://github.com/pret/pokecrystal/blob/master/gfx/battle/hp_exp_bar_border.png): ![image](https://raw.githubusercontent.com/pret/pokecrystal/master/gfx/battle/hp_exp_bar_border.png) **Fix:** Lower the ellipsis by two pixels: ![image](https://raw.githubusercontent.com/pret/pokecrystal/master/docs/images/hp_exp_bar_border.png) ### Two tiles in the `port` tileset are drawn incorrectly This is a mistake with the left-hand warp carpet corner tiles in [gfx/tilesets/port.png](https://github.com/pret/pokecrystal/blob/master/gfx/tilesets/port.png): ![image](https://raw.githubusercontent.com/pret/pokecrystal/master/gfx/tilesets/port.png) **Fix:** Adjust them to match the right-hand corner tiles: ![image](https://raw.githubusercontent.com/pret/pokecrystal/master/docs/images/port.png) ## The Ruins of Alph research center's roof color at night looks wrong The dungeons' map group mostly has indoor maps that don't need roof colors, but [maps/RuinsOfAlphOutside.blk](https://github.com/pret/pokecrystal/blob/master/maps/RuinsOfAlphOutside.blk) is an exception. It appears to have poorly-chosen roof colors: the morning/day colors are the same default gray as the unused group 0, and the night colors combine the light default gray and the dark red of Cinnabar's night roofs. ![image](https://raw.githubusercontent.com/pret/pokecrystal/master/docs/images/ruins_of_alph_outside.png) **Fix:** Edit [gfx/tilesets/roofs.pal](https://github.com/pret/pokecrystal/blob/master/gfx/tilesets/roofs.pal) to use the same red colors as Cinnabar (which are not actually seen in-game): ```diff ; group 3 (dungeons) - RGB 21,21,21, 11,11,11 ; morn/day - RGB 21,21,21, 17,08,07 ; nite + RGB 31,10,00, 18,06,00 ; morn/day + RGB 18,05,09, 17,08,07 ; nite ``` ![image](https://raw.githubusercontent.com/pret/pokecrystal/master/docs/images/ruins_of_alph_outside_cinnabar.png) ### A hatching Unown egg would not show the right letter This happens because both `GetEggFrontpic` and `GetHatchlingFrontpic` use `wBattleMonDVs`, but that's not initialized. They should use the current party mon's DVs instead. **Fix:** Edit both functions in [engine/pokemon/breeding.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokemon/breeding.asm): ```diff GetEggFrontpic: push de ld [wCurPartySpecies], a ld [wCurSpecies], a call GetBaseData - ld hl, wBattleMonDVs + ld a, MON_DVS + call GetPartyParamLocation predef GetUnownLetter pop de predef_jump GetMonFrontpic GetHatchlingFrontpic: push de ld [wCurPartySpecies], a ld [wCurSpecies], a call GetBaseData - ld hl, wBattleMonDVs + ld a, MON_DVS + call GetPartyParamLocation predef GetUnownLetter pop de predef_jump GetAnimatedFrontpic ``` ### Using a Park Ball in non-Contest battles has a corrupt animation ([Video](https://www.youtube.com/watch?v=v1ErZdLCIyU)) **Fix:** Edit `PokeBallEffect` in [engine/items/item_effects.asm](https://github.com/pret/pokecrystal/blob/master/engine/items/item_effects.asm): ```diff .room_in_party xor a ld [wWildMon], a - ld a, [wCurItem] - cp PARK_BALL + ld a, [wBattleType] + cp BATTLETYPE_CONTEST call nz, ReturnToBattle_UseBall ``` ### Battle transitions fail to account for the enemy's level ([Video](https://www.youtube.com/watch?v=eij_1060SMc)) There are three things wrong here: - `wEnemyMonLevel` isn't initialized yet - `wBattleMonLevel` gets overwritten after it's initialized by `FindFirstAliveMonAndStartBattle` - `wBattleMonLevel` isn't initialized until much later when the battle is with a trainer **Fix:** First, edit [engine/battle/battle_transition.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/battle_transition.asm): ```diff StartTrainerBattle_DetermineWhichAnimation: ; The screen flashes a different number of times depending on the level of ; your lead Pokemon relative to the opponent's. -; BUG: wBattleMonLevel and wEnemyMonLevel are not set at this point, so whatever -; values happen to be there will determine the animation. + ld a, [wOtherTrainerClass] + and a + jr z, .wild + farcall SetTrainerBattleLevel + +.wild + ld b, PARTY_LENGTH + ld hl, wPartyMon1HP + ld de, PARTYMON_STRUCT_LENGTH - 1 + +.loop + ld a, [hli] + or [hl] + jr nz, .okay + add hl, de + dec b + jr nz, .loop + +.okay + ld de, MON_LEVEL - MON_HP - 1 + add hl, de ld de, 0 - ld a, [wBattleMonLevel] + ld a, [hl] add 3 - ld hl, wEnemyMonLevel + ld hl, wCurPartyLevel cp [hl] jr nc, .not_stronger set TRANS_STRONGER_F, e .not_stronger ld a, [wEnvironment] cp CAVE jr z, .cave cp ENVIRONMENT_5 jr z, .cave cp DUNGEON jr z, .cave set TRANS_NO_CAVE_F, e .cave ld hl, .StartingPoints add hl, de ld a, [hl] ld [wJumptableIndex], a ret .StartingPoints: ; entries correspond to TRANS_* constants db BATTLETRANSITION_CAVE db BATTLETRANSITION_CAVE_STRONGER db BATTLETRANSITION_NO_CAVE db BATTLETRANSITION_NO_CAVE_STRONGER ``` Then edit [engine/battle/start_battle.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/start_battle.asm): ```diff FindFirstAliveMonAndStartBattle: xor a ldh [hMapAnims], a call DelayFrame - ld b, PARTY_LENGTH - ld hl, wPartyMon1HP - ld de, PARTYMON_STRUCT_LENGTH - 1 - -.loop - ld a, [hli] - or [hl] - jr nz, .okay - add hl, de - dec b - jr nz, .loop - -.okay - ld de, MON_LEVEL - MON_HP - add hl, de - ld a, [hl] - ld [wBattleMonLevel], a predef DoBattleTransition ``` Finally, edit [engine/battle/read_trainer_party.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/read_trainer_party.asm): ```diff INCLUDE "data/trainers/parties.asm" + +SetTrainerBattleLevel: + ld a, 255 + ld [wCurPartyLevel], a + + ld a, [wInBattleTowerBattle] + bit 0, a + ret nz + + ld a, [wLinkMode] + and a + ret nz + + ld a, [wOtherTrainerClass] + dec a + ld c, a + ld b, 0 + ld hl, TrainerGroups + add hl, bc + add hl, bc + ld a, [hli] + ld h, [hl] + ld l, a + + ld a, [wOtherTrainerID] + ld b, a +.skip_trainer + dec b + jr z, .got_trainer +.skip_party + ld a, [hli] + cp $ff + jr nz, .skip_party + jr .skip_trainer +.got_trainer + +.skip_name + ld a, [hli] + cp "@" + jr nz, .skip_name + + inc hl + ld a, [hl] + ld [wCurPartyLevel], a + ret ``` ### Some trainer NPCs have inconsistent overworld sprites *Some of these may have been intentional behavior; use your own judgment for whether to fix them.* Most trainer classes always use the same sprite and color for their overworld NPCs. There are some exceptions: - [maps/FastShipCabins_SE_SSE_CaptainsCabin.asm](https://github.com/pret/pokecrystal/blob/master/maps/FastShipCabins_SE_SSE_CaptainsCabin.asm): `TrainerPsychicRodney` should use `SPRITE_YOUNGSTER`, not `SPRITE_SUPER_NERD` - [maps/LakeOfRage.asm](https://github.com/pret/pokecrystal/blob/master/maps/LakeOfRage.asm): `TrainerFisherAndre` and `TrainerFisherRaymond` should use `PAL_NPC_GREEN`, not `PAL_NPC_BLUE` - [maps/Route13.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route13.asm): `TrainerHikerKenny` should use `PAL_NPC_BROWN`, not `PAL_NPC_RED` - [maps/Route44.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route44.asm): `TrainerBirdKeeperVance1` should use `PAL_NPC_BLUE`, not `PAL_NPC_GREEN` - [maps/Route44.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route44.asm): `TrainerPokemaniacZach` should use `PAL_NPC_BLUE`, not `PAL_NPC_GREEN` - [maps/UnionCaveB2F.asm](https://github.com/pret/pokecrystal/blob/master/maps/UnionCaveB2F.asm): `TrainerCooltrainermNick` should use `SPRITE_COOLTRAINER_M`, not `SPRITE_ROCKER` - [maps/FuchsiaPokecenter1F.asm](https://github.com/pret/pokecrystal/blob/master/maps/FuchsiaPokecenter1F.asm): `FuchsiaPokecenter1FNurseScript` should use `PAL_NPC_RED`, not `PAL_NPC_GREEN` Most of the NPCs in [maps/NationalParkBugContest.asm](https://github.com/pret/pokecrystal/blob/master/maps/NationalParkBugContest.asm) and [maps/Route36NationalParkGate.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route36NationalParkGate.asm) are also inconsistent with their trainers from other maps: - `BugCatchingContestant1AScript` and `BugCatchingContestant1BScript`: `BUG_CATCHER DON` from [maps/Route30.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route30.asm) should use `SPRITE_BUG_CATCHER` and `PAL_NPC_BROWN`, not `SPRITE_YOUNGSTER` and `PAL_NPC_RED` - `BugCatchingContestant2AScript` and `BugCatchingContestant2BScript`: `BUG_CATCHER ED` from [maps/Route2.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route2.asm) should use `SPRITE_BUG_CATCHER` and `PAL_NPC_BROWN`, not `SPRITE_YOUNGSTER` and `PAL_NPC_GREEN` - `BugCatchingContestant3AScript` and `BugCatchingContestant3BScript`: `COOLTRAINERM NICK` from [maps/UnionCaveB2F.asm](https://github.com/pret/pokecrystal/blob/master/maps/UnionCaveB2F.asm) should use `SPRITE_COOLTRAINER_M` and `PAL_NPC_RED`, not `SPRITE_ROCKER` and `PAL_NPC_BLUE` - `BugCatchingContestant4AScript` and `BugCatchingContestant4BScript`: `POKEFANM WILLIAM` from [maps/NationalPark.asm](https://github.com/pret/pokecrystal/blob/master/maps/NationalPark.asm) should use `PAL_NPC_RED`, not `PAL_NPC_BROWN` - `BugCatchingContestant5AScript` and `BugCatchingContestant5BScript`: `BUG_CATCHER BENNY` from [maps/AzaleaGym.asm](https://github.com/pret/pokecrystal/blob/master/maps/AzaleaGym.asm) should use `SPRITE_BUG_CATCHER` and `PAL_NPC_BROWN`, not `SPRITE_YOUNGSTER` and `PAL_NPC_RED` - `BugCatchingContestant7AScript` and `BugCatchingContestant7BScript`: `PICNICKER CINDY` from [maps/FuchsiaGym.asm](https://github.com/pret/pokecrystal/blob/master/maps/FuchsiaGym.asm) should use `PAL_NPC_GREEN`, not `PAL_NPC_BLUE` - `BugCatchingContestant8AScript` and `BugCatchingContestant8BScript`: `BUG_CATCHER JOSH` from [maps/AzaleaGym.asm](https://github.com/pret/pokecrystal/blob/master/maps/AzaleaGym.asm) should use `SPRITE_BUG_CATCHER` and `PAL_NPC_BROWN`, not `SPRITE_YOUNGSTER` and `PAL_NPC_RED` - `BugCatchingContestant9AScript` and `BugCatchingContestant9BScript`: `YOUNGSTER SAMUEL` from [maps/Route34.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route34.asm) should use `PAL_NPC_BLUE`, not `PAL_NPC_GREEN` (Note that [maps/Route8.asm](https://github.com/pret/pokecrystal/blob/master/maps/Route8.asm) has three `BIKER`s, `DWAYNE`, `HARRIS`, and `ZEKE`, that use `PAL_NPC_RED`, `PAL_NPC_GREEN`, and `PAL_NPC_BLUE` instead of `PAL_NPC_BROWN`; this is intentional since they're the "Kanto Pokémon Federation".) (The use of `SPRITE_ROCKER` instead of `SPRITE_COOLTRAINER_M` for `COOLTRAINERM NICK` may also be an intentional reference to the player's brother from the [Space World '97 beta](https://github.com/pret/pokegold-spaceworld).) ## Audio ### Slot machine payout sound effects cut each other off ([Video](https://www.youtube.com/watch?v=ojq3xqfRF6I)) **Fix:** Edit `SlotsAction_PayoutAnim` in [engine/games/slot_machine.asm](https://github.com/pret/pokecrystal/blob/master/engine/games/slot_machine.asm): ```diff .okay ld [hl], e dec hl ld [hl], d ld a, [wSlotsDelay] and $7 - ret z ; ret nz would be more appropriate + ret nz ld de, SFX_GET_COIN_FROM_SLOTS call PlaySFX ret ``` ### Team Rocket battle music is not used for Executives or Scientists **Fix:** Edit `PlayBattleMusic` in [engine/battle/start_battle.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/start_battle.asm): ```diff ld de, MUSIC_ROCKET_BATTLE cp GRUNTM jr z, .done cp GRUNTF jr z, .done + cp EXECUTIVEM + jr z, .done + cp EXECUTIVEF + jr z, .done + cp SCIENTIST + jr z, .done ``` ### No bump noise if standing on tile `$3E` **Fix:** Edit `DoPlayerMovement.CheckWarp` in [engine/overworld/player_movement.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/player_movement.asm): ```diff .CheckWarp: -; Bug: Since no case is made for STANDING here, it will check -; [.EdgeWarps + $ff]. This resolves to $3e. -; This causes wWalkingIntoEdgeWarp to be nonzero when standing on tile $3e, -; making bumps silent. - ld a, [wWalkingDirection] - ; cp STANDING - ; jr z, .not_warp + cp STANDING + jr z, .not_warp ld e, a ld d, 0 ld hl, .EdgeWarps add hl, de ld a, [wPlayerStandingTile] cp [hl] jr nz, .not_warp ld a, TRUE ld [wWalkingIntoEdgeWarp], a ld a, [wWalkingDirection] - ; This is in the wrong place. - cp STANDING - jr z, .not_warp ``` ### Playing Entei's Pokédex cry can distort Raikou's and Suicune's ([Video](https://www.youtube.com/watch?v=z305e4sIO24)) The exact cause of this bug is unknown. **Workaround:** Edit `DexEntryScreen_MenuActionJumptable.Cry` in [engine/pokedex/pokedex.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokedex/pokedex.asm): ```diff .Cry: - call Pokedex_GetSelectedMon - ld a, [wTempSpecies] - call GetCryIndex - ld e, c - ld d, b - call PlayCry + ld a, [wCurPartySpecies] + call PlayMonCry ret ``` ## Text ### Five-digit experience gain is printed incorrectly ([Video](https://www.youtube.com/watch?v=o54VjpAEoO8)) **Fix:** Edit `_BoostedExpPointsText` and `_ExpPointsText` in [data/text/common_2.asm](https://github.com/pret/pokecrystal/blob/master/data/text/common_2.asm): ```diff _BoostedExpPointsText:: text_start line "a boosted" cont "@" - text_decimal wStringBuffer2, 2, 4 + text_decimal wStringBuffer2, 2, 5 text " EXP. Points!" prompt _ExpPointsText:: text_start line "@" - text_decimal wStringBuffer2, 2, 4 + text_decimal wStringBuffer2, 2, 5 text " EXP. Points!" prompt ``` ### Only the first three evolution entries can have Stone compatibility reported correctly **Workaround:** Edit `PlacePartyMonEvoStoneCompatibility.DetermineCompatibility` in [engine/pokemon/party_menu.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokemon/party_menu.asm): ```diff .DetermineCompatibility: ld de, wStringBuffer1 ld a, BANK(EvosAttacksPointers) ld bc, 2 call FarCopyBytes ld hl, wStringBuffer1 ld a, [hli] ld h, [hl] ld l, a ld de, wStringBuffer1 ld a, BANK("Evolutions and Attacks") - ld bc, 10 + ld bc, STRING_BUFFER_LENGTH call FarCopyBytes ``` This supports up to six entries. ### `EVOLVE_STAT` can break Stone compatibility reporting **Fix:** Edit `PlacePartyMonEvoStoneCompatibility.DetermineCompatibility` in [engine/pokemon/party_menu.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokemon/party_menu.asm): ```diff .loop2 ld a, [hli] and a jr z, .nope + cp EVOLVE_STAT + jr nz, .not_four_bytes + inc hl +.not_four_bytes inc hl inc hl cp EVOLVE_ITEM jr nz, .loop2 ``` ### A "HOF Master!" title for 200-Time Famers is defined but inaccessible ([Video](https://www.youtube.com/watch?v=iHkWubvxmSg)) **Fix:** Edit `_HallOfFamePC.DisplayMonAndStrings` in [engine/events/halloffame.asm](https://github.com/pret/pokecrystal/blob/master/engine/events/halloffame.asm): ```diff ld a, [wHallOfFameTempWinCount] - cp HOF_MASTER_COUNT + 1 ; should be HOF_MASTER_COUNT + cp HOF_MASTER_COUNT jr c, .print_num_hof ld de, .HOFMaster hlcoord 1, 2 call PlaceString hlcoord 13, 2 jr .finish ``` ## Scripted events ### Clair can give TM24 Dragonbreath twice ([Video](https://www.youtube.com/watch?v=8BvBjqxmyOk)) **Fix:** Edit `DragonsDen1F_MapScripts` in [maps/DragonsDen1F.asm](https://github.com/pret/pokecrystal/blob/master/maps/DragonsDen1F.asm): ```diff def_callbacks + callback MAPCALLBACK_NEWMAP, .UnsetClairScene + +.UnsetClairScene: + setmapscene DRAGONS_DEN_B1F, SCENE_DRAGONSDENB1F_NOTHING + endcallback ``` ### Daisy's grooming doesn't always increase happiness This is a bug with `HaircutOrGrooming` in [engine/events/haircut.asm](https://github.com/pret/pokecrystal/blob/master/engine/events/haircut.asm): ```asm ; Bug: Subtracting $ff from $ff fails to set c. ; This can result in overflow into the next data array. ; In the case of getting a grooming from Daisy, we bleed ; into CopyPokemonName_Buffer1_Buffer3, which passes ; $d0 to ChangeHappiness and returns $73 to the script. ; The end result is that there is a 0.4% chance your ; Pokemon's happiness will not change at all. .loop sub [hl] jr c, .ok inc hl inc hl inc hl jr .loop .ok inc hl ld a, [hli] ld [wScriptVar], a ld c, [hl] call ChangeHappiness ret ... INCLUDE "data/events/happiness_probabilities.asm" CopyPokemonName_Buffer1_Buffer3: ld hl, wStringBuffer1 ld de, wStringBuffer3 ld bc, MON_NAME_LENGTH jp CopyBytes ``` **Fix:** Edit [data/events/happiness_probabilities.asm](https://github.com/pret/pokecrystal/blob/master/data/events/happiness_probabilities.asm): ```diff HappinessData_DaisysGrooming: - db -1, 2, HAPPINESS_GROOMING ; 99.6% chance + db 50 percent, 2, HAPPINESS_GROOMING ; 50% chance + db -1, 2, HAPPINESS_GROOMING ; 50% chance ``` ### Magikarp in Lake of Rage are shorter, not longer **Fix:** Edit `LoadEnemyMon.CheckMagikarpArea` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff .CheckMagikarpArea: -; The "jr z" checks are supposed to be "jr nz". - -; Instead, all maps in GROUP_LAKE_OF_RAGE (Mahogany area) -; and Routes 20 and 44 are treated as Lake of Rage. - -; This also means Lake of Rage Magikarp can be smaller than ones -; caught elsewhere rather than the other way around. - -; Intended behavior enforces a minimum size at Lake of Rage. -; The real behavior prevents a minimum size in the Lake of Rage area. - -; Moreover, due to the check not being translated to feet+inches, all Magikarp -; smaller than 4'0" may be caught by the filter, a lot more than intended. ld a, [wMapGroup] cp GROUP_LAKE_OF_RAGE - jr z, .Happiness + jr nz, .Happiness ld a, [wMapNumber] cp MAP_LAKE_OF_RAGE - jr z, .Happiness + jr nz, .Happiness ``` ### Magikarp length limits have a unit conversion error **Fix:** Edit `LoadEnemyMon.CheckMagikarpArea` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm): ```diff ; Get Magikarp's length ld de, wEnemyMonDVs ld bc, wPlayerID callfar CalcMagikarpLength ; No reason to keep going if length > 1536 mm (i.e. if HIGH(length) > 6 feet) ld a, [wMagikarpLength] - cp HIGH(1536) ; should be "cp 5", since 1536 mm = 5'0", but HIGH(1536) = 6 + cp 5 jr nz, .CheckMagikarpArea ; 5% chance of skipping both size checks call Random cp 5 percent jr c, .CheckMagikarpArea ; Try again if length >= 1616 mm (i.e. if LOW(length) >= 4 inches) ld a, [wMagikarpLength + 1] - cp LOW(1616) ; should be "cp 4", since 1616 mm = 5'4", but LOW(1616) = 80 + cp 4 jr nc, .GenerateDVs ; 20% chance of skipping this check call Random cp 20 percent - 1 jr c, .CheckMagikarpArea ; Try again if length >= 1600 mm (i.e. if LOW(length) >= 3 inches) ld a, [wMagikarpLength + 1] - cp LOW(1600) ; should be "cp 3", since 1600 mm = 5'3", but LOW(1600) = 64 + cp 3 jr nc, .GenerateDVs ``` **Better fix:** Rewrite the whole system to use millimeters instead of feet and inches, since they have better precision (1 in = 25.4 mm); and only convert from metric to imperial units for display purposes (or don't, of course). ### Magikarp lengths can be miscalculated **Fix:** Edit `CalcMagikarpLength.BCLessThanDE` in [engine/events/magikarp.asm](https://github.com/pret/pokecrystal/blob/master/engine/events/magikarp.asm): ```diff .BCLessThanDE: -; Intention: Return bc < de. -; Reality: Return b < d. ld a, b cp d ret c - ret nc ; whoops ld a, c cp e ret ``` ### `CheckOwnMon` only checks the first five letters of OT names ([Video](https://www.youtube.com/watch?v=GVTTmReM4nQ)) This bug can allow you to talk to Eusine in Celadon City and encounter Ho-Oh with only traded legendary beasts. **Fix:** Edit `CheckOwnMon` in [engine/pokemon/search.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokemon/search.asm): ```diff ; check OT -; This only checks five characters, which is fine for the Japanese version, -; but in the English version the player name is 7 characters, so this is wrong. ld hl, wPlayerName -rept NAME_LENGTH_JAPANESE - 2 ; should be PLAYER_NAME_LENGTH - 2 +rept PLAYER_NAME_LENGTH - 2 ld a, [de] cp [hl] jr nz, .notfound cp "@" jr z, .found ; reached end of string inc hl inc de endr ld a, [de] cp [hl] jr z, .found ``` ### `CheckOwnMonAnywhere` does not check the Day-Care *This may have been intentional behavior; use your own judgment for whether to fix it.* This bug can prevent you from talking to Eusine in Celadon City or encountering Ho-Oh when a caught legendary beast is in the Day-Care. **Fix:** Edit `CheckOwnMonAnywhere` in [engine/pokemon/search.asm](https://github.com/pret/pokecrystal/blob/master/engine/pokemon/search.asm): ```diff ; If there are no monsters in the party, ; the player must not own any yet. ld a, [wPartyCount] and a ret z + + ld hl, wBreedMon1Species + ld bc, wBreedMon1OT + call CheckOwnMon + ret c ; found! + + ld hl, wBreedMon2Species + ld bc, wBreedMon2OT + call CheckOwnMon + ret c ; found! ``` ### The unused `phonecall` script command may crash The `phonecall` script command calls the `PhoneCall` routine, which calls the `BrokenPlaceFarString` routine; this switches banks without being in bank 0, so it would start running arbitrary data as code. **Fix:** Edit `PhoneCall.CallerTextboxWithName` in [engine/phone/phone.asm](https://github.com/pret/pokecrystal/blob/master/engine/phone/phone.asm): ```diff - ld a, [wPhoneScriptBank] - ld b, a ld a, [wPhoneCaller] ld e, a ld a, [wPhoneCaller + 1] ld d, a - call BrokenPlaceFarString + ld a, [wPhoneScriptBank] + call PlaceFarString ret ``` You can also delete the now-unused `BrokenPlaceFarString` routine. ## Internal engine routines ### Saves corrupted by mid-save shutoff are not handled ([Video 1](https://www.youtube.com/watch?v=ukqtK0l6bu0), [Video 2](https://www.youtube.com/watch?v=c2zHd1BPtvc)) This does not have a simple and accurate fix. It would involve redesigning parts of the save system for Pokémon boxes. ### `ScriptCall` can overflow `wScriptStack` and crash **Fix:** Edit `ScriptCall` in [engine/overworld/scripting.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/scripting.asm): ```diff ScriptCall: -; Bug: The script stack has a capacity of 5 scripts, yet there is -; nothing to stop you from pushing a sixth script. The high part -; of the script address can then be overwritten by modifications -; to wScriptDelay, causing the script to return to the rst/interrupt -; space. - + ld hl, wScriptStackSize + ld a, [hl] + cp 5 + ret nc push de - ld hl, wScriptStackSize - ld e, [hl] inc [hl] + ld e, a ld d, 0 ld hl, wScriptStack add hl, de add hl, de add hl, de pop de ld a, [wScriptBank] ld [hli], a ld a, [wScriptPos] ld [hli], a ld a, [wScriptPos + 1] ld [hl], a ld a, b ld [wScriptBank], a ld a, e ld [wScriptPos], a ld a, d ld [wScriptPos + 1], a ret ``` ### `LoadSpriteGFX` does not limit the capacity of `UsedSprites` **Fix:** Edit `LoadSpriteGFX` in [engine/overworld/overworld.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/overworld.asm): ```diff LoadSpriteGFX: -; Bug: b is not preserved, so it's useless as a next count. -; Uncomment the lines below to fix. - ld hl, wUsedSprites ld b, SPRITE_GFX_LIST_CAPACITY .loop ld a, [hli] and a jr z, .done push hl call .LoadSprite pop hl ld [hli], a dec b jr nz, .loop .done ret .LoadSprite: - ; push bc + push bc call GetSprite - ; pop bc + pop bc ld a, l ret ``` ### `ChooseWildEncounter` doesn't really validate the wild Pokémon species **Fix:** Edit `ChooseWildEncounter` in [engine/overworld/wildmons.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/wildmons.asm): ```diff .ok ld a, b ld [wCurPartyLevel], a ld b, [hl] - ; ld a, b + ld a, b call ValidateTempWildMonSpecies jr c, .nowildbattle - ld a, b ; This is in the wrong place. cp UNOWN jr nz, .done ``` ### `TryObjectEvent` arbitrary code execution **Fix:** Edit `TryObjectEvent` in [engine/overworld/events.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/events.asm): ```diff -; Bug: If IsInArray returns nc, data at bc will be executed as code. push bc ld de, 3 ld hl, .pointers call IsInArray - jr nc, .nope pop bc + jr nc, .nope inc hl ld a, [hli] ld h, [hl] ld l, a jp hl .nope - ; pop bc xor a ret ``` ### `ReadObjectEvents` overflows into `wObjectMasks` **Fix:** Edit `ReadObjectEvents` in [home/map.asm](https://github.com/pret/pokecrystal/blob/master/home/map.asm): ```diff -; get NUM_OBJECTS - [wCurMapObjectEventCount] +; get NUM_OBJECTS - [wCurMapObjectEventCount] - 1 ld a, [wCurMapObjectEventCount] ld c, a - ld a, NUM_OBJECTS ; - 1 + ld a, NUM_OBJECTS - 1 sub c jr z, .skip - ; jr c, .skip + jr c, .skip ; could have done "inc hl" instead ld bc, 1 add hl, bc -; Fill the remaining sprite IDs and y coords with 0 and -1, respectively. -; Bleeds into wObjectMasks due to a bug. Uncomment the above code to fix. ld bc, MAPOBJECT_LENGTH .loop ld [hl], 0 inc hl ld [hl], -1 dec hl add hl, bc dec a jr nz, .loop ``` ### `ClearWRAM` only clears WRAM bank 1 **Fix:** Edit `ClearWRAM` in [home/init.asm](https://github.com/pret/pokecrystal/blob/master/home/init.asm): ```diff ClearWRAM:: ; Wipe swappable WRAM banks (1-7) ; Assumes CGB or AGB ld a, 1 .bank_loop push af ldh [rSVBK], a xor a ld hl, WRAM1_Begin ld bc, WRAM1_End - WRAM1_Begin call ByteFill pop af inc a cp 8 - jr nc, .bank_loop ; Should be jr c + jr c, .bank_loop ret ``` ### `BattleAnimCmd_ClearObjs` only clears the first 6⅔ objects **Fix:** Edit `BattleAnimCmd_ClearObjs` in [engine/battle_anims/anim_commands.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle_anims/anim_commands.asm): ```diff BattleAnimCmd_ClearObjs: -; BUG: This function only clears the first 6⅔ objects ld hl, wActiveAnimObjects - ld a, $a0 ; should be NUM_ANIM_OBJECTS * BATTLEANIMSTRUCT_LENGTH + ld a, NUM_ANIM_OBJECTS * BATTLEANIMSTRUCT_LENGTH .loop ld [hl], 0 inc hl dec a jr nz, .loop ret ```