Pokémon Crystal (pret/pokecrystal)

Crystal's type chart (TypeMatchups) has 108 non-neutral rows over 17 types, then a -2 marker, Normal→Ghost and Fighting→Ghost ×0, and a -1 end. pokecrystal/type-chart

Value

{
 "kind": "type-chart",
 "types": [
  "Normal",
  "Fighting",
  "Flying",
  "Poison",
  "Ground",
  "Rock",
  "Bug",
  "Ghost",
  "Steel",
  "Fire",
  "Water",
  "Grass",
  "Electric",
  "Psychic",
  "Ice",
  "Dragon",
  "Dark"
 ],
 "matchups": [
  [
   "Normal",
   "Rock",
   5,
   3
  ],
  [
   "Normal",
   "Steel",
   5,
   4
  ],
  [
   "Fire",
   "Fire",
   5,
   5
  ],
  [
   "Fire",
   "Water",
   5,
   6
  ],
  [
   "Fire",
   "Grass",
   20,
   7
  ],
  [
   "Fire",
   "Ice",
   20,
   8
  ],
  [
   "Fire",
   "Bug",
   20,
   9
  ],
  [
   "Fire",
   "Rock",
   5,
   10
  ],
  [
   "Fire",
   "Dragon",
   5,
   11
  ],
  [
   "Fire",
   "Steel",
   20,
   12
  ],
  [
   "Water",
   "Fire",
   20,
   13
  ],
  [
   "Water",
   "Water",
   5,
   14
  ],
  [
   "Water",
   "Grass",
   5,
   15
  ],
  [
   "Water",
   "Ground",
   20,
   16
  ],
  [
   "Water",
   "Rock",
   20,
   17
  ],
  [
   "Water",
   "Dragon",
   5,
   18
  ],
  [
   "Electric",
   "Water",
   20,
   19
  ],
  [
   "Electric",
   "Electric",
   5,
   20
  ],
  [
   "Electric",
   "Grass",
   5,
   21
  ],
  [
   "Electric",
   "Ground",
   0,
   22
  ],
  [
   "Electric",
   "Flying",
   20,
   23
  ],
  [
   "Electric",
   "Dragon",
   5,
   24
  ],
  [
   "Grass",
   "Fire",
   5,
   25
  ],
  [
   "Grass",
   "Water",
   20,
   26
  ],
  [
   "Grass",
   "Grass",
   5,
   27
  ],
  [
   "Grass",
   "Poison",
   5,
   28
  ],
  [
   "Grass",
   "Ground",
   20,
   29
  ],
  [
   "Grass",
   "Flying",
   5,
   30
  ],
  [
   "Grass",
   "Bug",
   5,
   31
  ],
  [
   "Grass",
   "Rock",
   20,
   32
  ],
  [
   "Grass",
   "Dragon",
   5,
   33
  ],
  [
   "Grass",
   "Steel",
   5,
   34
  ],
  [
   "Ice",
   "Water",
   5,
   35
  ],
  [
   "Ice",
   "Grass",
   20,
   36
  ],
  [
   "Ice",
   "Ice",
   5,
   37
  ],
  [
   "Ice",
   "Ground",
   20,
   38
  ],
  [
   "Ice",
   "Flying",
   20,
   39
  ],
  [
   "Ice",
   "Dragon",
   20,
   40
  ],
  [
   "Ice",
   "Steel",
   5,
   41
  ],
  [
   "Ice",
   "Fire",
   5,
   42
  ],
  [
   "Fighting",
   "Normal",
   20,
   43
  ],
  [
   "Fighting",
   "Ice",
   20,
   44
  ],
  [
   "Fighting",
   "Poison",
   5,
   45
  ],
  [
   "Fighting",
   "Flying",
   5,
   46
  ],
  [
   "Fighting",
   "Psychic",
   5,
   47
  ],
  [
   "Fighting",
   "Bug",
   5,
   48
  ],
  [
   "Fighting",
   "Rock",
   20,
   49
  ],
  [
   "Fighting",
   "Dark",
   20,
   50
  ],
  [
   "Fighting",
   "Steel",
   20,
   51
  ],
  [
   "Poison",
   "Grass",
   20,
   52
  ],
  [
   "Poison",
   "Poison",
   5,
   53
  ],
  [
   "Poison",
   "Ground",
   5,
   54
  ],
  [
   "Poison",
   "Rock",
   5,
   55
  ],
  [
   "Poison",
   "Ghost",
   5,
   56
  ],
  [
   "Poison",
   "Steel",
   0,
   57
  ],
  [
   "Ground",
   "Fire",
   20,
   58
  ],
  [
   "Ground",
   "Electric",
   20,
   59
  ],
  [
   "Ground",
   "Grass",
   5,
   60
  ],
  [
   "Ground",
   "Poison",
   20,
   61
  ],
  [
   "Ground",
   "Flying",
   0,
   62
  ],
  [
   "Ground",
   "Bug",
   5,
   63
  ],
  [
   "Ground",
   "Rock",
   20,
   64
  ],
  [
   "Ground",
   "Steel",
   20,
   65
  ],
  [
   "Flying",
   "Electric",
   5,
   66
  ],
  [
   "Flying",
   "Grass",
   20,
   67
  ],
  [
   "Flying",
   "Fighting",
   20,
   68
  ],
  [
   "Flying",
   "Bug",
   20,
   69
  ],
  [
   "Flying",
   "Rock",
   5,
   70
  ],
  [
   "Flying",
   "Steel",
   5,
   71
  ],
  [
   "Psychic",
   "Fighting",
   20,
   72
  ],
  [
   "Psychic",
   "Poison",
   20,
   73
  ],
  [
   "Psychic",
   "Psychic",
   5,
   74
  ],
  [
   "Psychic",
   "Dark",
   0,
   75
  ],
  [
   "Psychic",
   "Steel",
   5,
   76
  ],
  [
   "Bug",
   "Fire",
   5,
   77
  ],
  [
   "Bug",
   "Grass",
   20,
   78
  ],
  [
   "Bug",
   "Fighting",
   5,
   79
  ],
  [
   "Bug",
   "Poison",
   5,
   80
  ],
  [
   "Bug",
   "Flying",
   5,
   81
  ],
  [
   "Bug",
   "Psychic",
   20,
   82
  ],
  [
   "Bug",
   "Ghost",
   5,
   83
  ],
  [
   "Bug",
   "Dark",
   20,
   84
  ],
  [
   "Bug",
   "Steel",
   5,
   85
  ],
  [
   "Rock",
   "Fire",
   20,
   86
  ],
  [
   "Rock",
   "Ice",
   20,
   87
  ],
  [
   "Rock",
   "Fighting",
   5,
   88
  ],
  [
   "Rock",
   "Ground",
   5,
   89
  ],
  [
   "Rock",
   "Flying",
   20,
   90
  ],
  [
   "Rock",
   "Bug",
   20,
   91
  ],
  [
   "Rock",
   "Steel",
   5,
   92
  ],
  [
   "Ghost",
   "Normal",
   0,
   93
  ],
  [
   "Ghost",
   "Psychic",
   20,
   94
  ],
  [
   "Ghost",
   "Dark",
   5,
   95
  ],
  [
   "Ghost",
   "Steel",
   5,
   96
  ],
  [
   "Ghost",
   "Ghost",
   20,
   97
  ],
  [
   "Dragon",
   "Dragon",
   20,
   98
  ],
  [
   "Dragon",
   "Steel",
   5,
   99
  ],
  [
   "Dark",
   "Fighting",
   5,
   100
  ],
  [
   "Dark",
   "Psychic",
   20,
   101
  ],
  [
   "Dark",
   "Ghost",
   20,
   102
  ],
  [
   "Dark",
   "Dark",
   5,
   103
  ],
  [
   "Dark",
   "Steel",
   5,
   104
  ],
  [
   "Steel",
   "Fire",
   5,
   105
  ],
  [
   "Steel",
   "Water",
   5,
   106
  ],
  [
   "Steel",
   "Electric",
   5,
   107
  ],
  [
   "Steel",
   "Ice",
   20,
   108
  ],
  [
   "Steel",
   "Rock",
   20,
   109
  ],
  [
   "Steel",
   "Steel",
   5,
   110
  ]
 ],
 "foresightOnly": [
  [
   "Normal",
   "Ghost",
   0,
   115
  ],
  [
   "Fighting",
   "Ghost",
   0,
   116
  ]
 ],
 "foresightMarkerLine": 112
}

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · data/types/type_matchups.asm#L1-L118 db -2 ; end (with Foresight) ; Foresight removes Ghost's immunities. db NORMAL, GHOST, NO_EFFECT db FIGHTING, GHOST, NO_EFFECTpokecrystal: disassembly of Pokémon Crystal · constants/type_constants.asm#L7-L37 — type order used for `types` (constants that appear in at least one row)Checked by claude-agent, 2026-10-20 — read every row of data/types/type_matchups.asm L1–L118 and the type constants at the pinned commit; probes/pokemon-types/type-charts.mjs re-parses the table and diffs it against this value

Rows are [attacking, defending, stored multiplier, line]; foresightOnly holds the rows after the -2 marker (pokecrystal/foresight).

Cited by: Pokémon Crystal, Type effectiveness

Multipliers are unchanged from Red/Blue: scaled by 10, with SUPER_EFFECTIVE 20, NOT_VERY_EFFECTIVE 05, NO_EFFECT 00, and EFFECTIVE 10. pokecrystal/multiplier-encoding

Value

{
 "kind": "multiplier-encoding",
 "neutral": 10,
 "super": 20,
 "notVery": 5,
 "none": 0
}

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · constants/battle_constants.asm#L20-L25; type effectiveness factors, scaled by 10 DEF SUPER_EFFECTIVE EQU 20Checked by claude-agent, 2026-10-20 — read the constants at the pinned commit

Cited by: Pokémon Crystal, Type effectiveness

Crystal's type constants add STEEL (physical), DARK (special), and an unused CURSE_TYPE named “???”; BIRD remains, still with no rows. pokecrystal/new-types

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · constants/type_constants.asm#L9-L37 const STEEL … const CURSE_TYPE … const DARKpokecrystal: disassembly of Pokémon Crystal · data/types/names.asm#L37CurseType: db "???@"Checked by claude-agent, 2026-10-20 — read the constants and names; the probe lists the type constants with no table rows (Bird, Curse)Probe: probes/pokemon-types/type-charts.mjs

Cited by: Pokémon Crystal, Type effectiveness

BattleCommand_Stab applies weather and badge type boosts, then STAB ( $damage + ⌊ damage / 2 ⌋$ if either attacker type matches), then the type chart. pokecrystal/stab

About: Pokémon Crystal Same-type attack bonus

Value

{
 "kind": "stab",
 "form": "half-add"
}

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1251-L1288 farcall DoWeatherModifiers … farcall DoBadgeTypeBoosts … srl b rr c add hl, bcChecked by claude-agent, 2026-10-20 — read BattleCommand_Stab L1214–L1396 at the pinned commit

Cited by: Pokémon Crystal, Same-type attack bonus, Type effectiveness

A comment in pokecrystal's BattleCommand_Stab expands STAB as “Same Type Attack Bonus”. pokecrystal/stab-name

About: Pokémon Crystal Same-type attack bonus

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1214-L1215BattleCommand_Stab: ; STAB = Same Type Attack BonusChecked by claude, 2026-10-20 — read the routine's first lines at the pinned commit

The comment is the disassemblers', not the game's. No source here says who coined the term.

Cited by: Same-type attack bonus

Struggle returns from BattleCommand_Stab at once, so it skips weather, badge boosts, STAB, and the type chart. pokecrystal/struggle-skips

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1216-L1219 ld a, BATTLE_VARS_MOVE_ANIM call GetBattleVar cp STRUGGLE ret zChecked by claude-agent, 2026-10-20 — read the routine entry

Cited by: Same-type attack bonus, Type effectiveness

Each matching row computes $damage \times value$ ; a nonzero product becomes $⌊ product / 10 ⌋$ , raised to 1 if that truncates to 0. pokecrystal/type-step

Value

{
 "kind": "type-step",
 "div": 10,
 "zero": "min1",
 "immune": "miss"
}

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1312-L1386 jr z, .ok ; This is a very convoluted way to get back that we've essentially dealt no damage. ; Take the product and divide it by 10. … ld a, 1 ldh [hMultiplicand + 2], aChecked by claude-agent, 2026-10-20 — read .SkipForesightCheck through .SkipType; checked in ram/hram.asm L63–L82 that hMultiplicand + 1/+2 alias hQuotient + 2/+3 (and hProduct + 2/+3), so the stored bytes are the quotient (or the zero product)

Cited by: Pokémon Crystal, Type effectiveness

A ×0 row now marks the attack as missed outright, instead of relying on the damage reaching 0. pokecrystal/immunity-miss

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1329-L1336; If the target is immune to the move, treat it as a miss and calculate the damage as 0 ld a, [hl] and a jr nz, .NotImmune inc a ld [wAttackMissed], aChecked by claude-agent, 2026-10-20 — read the .GotMatchup code

Cited by: Pokémon Crystal, Type effectiveness

A ×¼ hit no longer truncates to a miss: 2 damage through two ½ rows gives ⌊2 × 5 / 10⌋ = 1, then ⌊1 × 5 / 10⌋ = 0, raised to 1. pokecrystal/quarter-min-one

T4 reproducedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1361-L1373Checked by claude-agent, 2026-10-20 — the probe replays the modeled step for a Grass move against a Grass/Poison defenderProbe: probes/pokemon-types/type-charts.mjs

Cited by: Type effectiveness

Against an identified (Foresight) target, the loop stops at the -2 marker, skipping the Normal→Ghost and Fighting→Ghost immunities after it. pokecrystal/foresight

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1302-L1310 ; foresight cp -2 jr nz, .SkipForesightCheck ld a, BATTLE_VARS_SUBSTATUS1_OPP call GetBattleVar bit SUBSTATUS_IDENTIFIED, a jr nz, .endpokecrystal: disassembly of Pokémon Crystal · data/types/type_matchups.asm#L112-L116Checked by claude-agent, 2026-10-20 — read the loop and the table tail

Cited by: Pokémon Crystal, Type effectiveness

After the loop, CheckTypeMatchup's combined value ( $m = ⌊ m \times row / 10 ⌋$ from 10) replaces the effectiveness byte, so the text reflects every row: ×4 is 40, ×¼ is 2, and ½ with 2× is 10. pokecrystal/effectiveness-message

Value

{
 "kind": "message",
 "rule": "combined"
}

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1388-L1396 call BattleCheckTypeMatchup ld a, [wTypeMatchup] ld b, a ld a, [wTypeModifier] and STAB_DAMAGE or b ld [wTypeModifier], apokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1405-L1471 — CheckTypeMatchup seeds wTypeMatchup with EFFECTIVE and folds each row in with Multiply / Divide by 10pokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L2324-L2333 — BattleCommand_SuperEffectiveText compares the masked byte with EFFECTIVEpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L2197-L2202 — GetFailureResultText picks DoesntAffectText when the masked byte is 0Checked by claude-agent, 2026-10-20 — read the end of BattleCommand_Stab, CheckTypeMatchup, BattleCommand_SuperEffectiveText and GetFailureResultText

Cited by: Pokémon Crystal, Type effectiveness

An Ice move against Water/Flying (½ at L35, 2× at L39) prints no effectiveness text: the combined value goes 10 → 5 → 10. pokecrystal/message-net-neutral

T4 reproducedpokecrystal: disassembly of Pokémon Crystal · data/types/type_matchups.asm#L35-L39Checked by claude-agent, 2026-10-20 — the probe replays the combined-value ruleProbe: probes/pokemon-types/type-charts.mjs

Cited by: Type effectiveness

Row order still matters: an Ice move against Water/Flying takes 3 damage to 1, then 2 (½ row at L35, 2× at L39). pokecrystal/truncation-order

T4 reproducedpokecrystal: disassembly of Pokémon Crystal · data/types/type_matchups.asm#L35-L39 db ICE, WATER, NOT_VERY_EFFECTIVE … db ICE, FLYING, SUPER_EFFECTIVEChecked by claude-agent, 2026-10-20 — read the rows and the step code; the probe replays itProbe: probes/pokemon-types/type-charts.mjs

Cited by: Type effectiveness

Crystal's type chart makes Ghost-type moves super effective on Psychic types. pokecrystal/ghost-psychic

Value: 2 ×

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · data/types/type_matchups.asm#L94db GHOST, PSYCHIC_TYPE, SUPER_EFFECTIVEChecked by claude-agent, 2026-10-20 — read L94 at the pinned commit

Cited by: Type effectiveness

Crystal's table adds Steel and Dark and changes four Red/Blue matchups: Poison→Bug ×2 → ×1, Bug→Poison ×2 → ×½, Ghost→Psychic ×0 → ×2, and Ice→Fire ×1 → ×½. pokecrystal/chart-diff

Value

{
 "kind": "chart-diff",
 "from": "pokered",
 "newTypes": [
  "Steel",
  "Dark"
 ],
 "changed": [
  [
   "Poison",
   "Bug",
   20,
   10
  ],
  [
   "Bug",
   "Poison",
   20,
   5
  ],
  [
   "Ghost",
   "Psychic",
   0,
   20
  ],
  [
   "Ice",
   "Fire",
   10,
   5
  ]
 ]
}

T4 reproducedpokered: disassembly of Pokémon Red and Blue · data/types/type_matchups.asm#L1-L85pokecrystal: disassembly of Pokémon Crystal · data/types/type_matchups.asm#L1-L118Type/Type chart · Changes: Between Generations I and IIThe Dark and Steel types were introduced. Bug was made ½× against Poison instead of 2×. Poison was made 1× against Bug instead of 2×. Ghost was made 2× against Psychic instead of 0×. Ice was made ½× against Fire instead of 1×.Checked by claude-agent, 2026-10-20 — the probe parses both tables and compares every attacker × defender cell; the result matches Bulbapedia's listProbe: probes/pokemon-types/type-charts.mjs

Row order also changed: Red/Blue's table is loosely grouped, and Crystal's is grouped by attacking type. The probe compares stored values and counts the Foresight rows as active.

Cited by: Pokémon Crystal, Type effectiveness

Type still picks the stats: Steel is physical (below SPECIAL); Dark is special, using Special Attack against Special Defense. pokecrystal/physical-special-by-type

About: Pokémon Crystal Damage formula

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L2543-L2545 cp SPECIAL jr nc, .specialpokecrystal: disassembly of Pokémon Crystal · constants/type_constants.asm#L9-L35Checked by claude-agent, 2026-10-20 — read PlayerAttackDamage and the type constants

Cited by: Damage formula, Type effectiveness

A plain damaging move runs critical, damagestats, damagecalc (base formula, item boosts, and critical ×2), stab (weather, badges, STAB, and type rows), damagevariation, and then checkhit (accuracy). pokecrystal/damage-order

About: Pokémon Crystal Damage formula

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · data/moves/effects.asm#L5-L14NormalHit: checkobedience usedmovetext doturn critical damagestats damagecalc stab damagevariation checkhitpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L2983-L3023 — item boosts and the call to .CriticalMultiplier (L3108–L3120, doubles the damage) inside BattleCommand_DamageCalcChecked by claude-agent, 2026-10-20 — read the NormalHit effect script and BattleCommand_DamageCalc

Cited by: Damage formula, Type effectiveness

The random factor is unchanged from Red/Blue, a random byte from 217 to 255 over 255. pokecrystal/random-factor

About: Pokémon Crystal Damage formula

Value

[
 217,
 255
]

T3 code-verifiedpokecrystal: disassembly of Pokémon Crystal · engine/battle/effect_commands.asm#L1496-L1544 cp 85 percent + 1 … ld a, 100 percentChecked by claude-agent, 2026-10-20 — read BattleCommand_DamageVariation and macros/data.asm L23 (percent = * $ff / 100)

Cited by: Damage formula, Type effectiveness