Pokémon Red and Blue (pret/pokered)

Red and Blue's type chart (TypeEffects) has 82 non-neutral (attacker, defender, multiplier) rows over 15 types, ended by -1; unlisted pairs are neutral. pokered/type-chart

{
 "kind": "type-chart",
 "types": [
  "Normal",
  "Fighting",
  "Flying",
  "Poison",
  "Ground",
  "Rock",
  "Bug",
  "Ghost",
  "Fire",
  "Water",
  "Grass",
  "Electric",
  "Psychic",
  "Ice",
  "Dragon"
 ],
 "matchups": [
  [
   "Water",
   "Fire",
   20,
   3
  ],
  [
   "Fire",
   "Grass",
   20,
   4
  ],
  [
   "Fire",
   "Ice",
   20,
   5
  ],
  [
   "Grass",
   "Water",
   20,
   6
  ],
  [
   "Electric",
   "Water",
   20,
   7
  ],
  [
   "Water",
   "Rock",
   20,
   8
  ],
  [
   "Ground",
   "Flying",
   0,
   9
  ],
  [
   "Water",
   "Water",
   5,
   10
  ],
  [
   "Fire",
   "Fire",
   5,
   11
  ],
  [
   "Electric",
   "Electric",
   5,
   12
  ],
  [
   "Ice",
   "Ice",
   5,
   13
  ],
  [
   "Grass",
   "Grass",
   5,
   14
  ],
  [
   "Psychic",
   "Psychic",
   5,
   15
  ],
  [
   "Fire",
   "Water",
   5,
   16
  ],
  [
   "Grass",
   "Fire",
   5,
   17
  ],
  [
   "Water",
   "Grass",
   5,
   18
  ],
  [
   "Electric",
   "Grass",
   5,
   19
  ],
  [
   "Normal",
   "Rock",
   5,
   20
  ],
  [
   "Normal",
   "Ghost",
   0,
   21
  ],
  [
   "Ghost",
   "Ghost",
   20,
   22
  ],
  [
   "Fire",
   "Bug",
   20,
   23
  ],
  [
   "Fire",
   "Rock",
   5,
   24
  ],
  [
   "Water",
   "Ground",
   20,
   25
  ],
  [
   "Electric",
   "Ground",
   0,
   26
  ],
  [
   "Electric",
   "Flying",
   20,
   27
  ],
  [
   "Grass",
   "Ground",
   20,
   28
  ],
  [
   "Grass",
   "Bug",
   5,
   29
  ],
  [
   "Grass",
   "Poison",
   5,
   30
  ],
  [
   "Grass",
   "Rock",
   20,
   31
  ],
  [
   "Grass",
   "Flying",
   5,
   32
  ],
  [
   "Ice",
   "Water",
   5,
   33
  ],
  [
   "Ice",
   "Grass",
   20,
   34
  ],
  [
   "Ice",
   "Ground",
   20,
   35
  ],
  [
   "Ice",
   "Flying",
   20,
   36
  ],
  [
   "Fighting",
   "Normal",
   20,
   37
  ],
  [
   "Fighting",
   "Poison",
   5,
   38
  ],
  [
   "Fighting",
   "Flying",
   5,
   39
  ],
  [
   "Fighting",
   "Psychic",
   5,
   40
  ],
  [
   "Fighting",
   "Bug",
   5,
   41
  ],
  [
   "Fighting",
   "Rock",
   20,
   42
  ],
  [
   "Fighting",
   "Ice",
   20,
   43
  ],
  [
   "Fighting",
   "Ghost",
   0,
   44
  ],
  [
   "Poison",
   "Grass",
   20,
   45
  ],
  [
   "Poison",
   "Poison",
   5,
   46
  ],
  [
   "Poison",
   "Ground",
   5,
   47
  ],
  [
   "Poison",
   "Bug",
   20,
   48
  ],
  [
   "Poison",
   "Rock",
   5,
   49
  ],
  [
   "Poison",
   "Ghost",
   5,
   50
  ],
  [
   "Ground",
   "Fire",
   20,
   51
  ],
  [
   "Ground",
   "Electric",
   20,
   52
  ],
  [
   "Ground",
   "Grass",
   5,
   53
  ],
  [
   "Ground",
   "Bug",
   5,
   54
  ],
  [
   "Ground",
   "Rock",
   20,
   55
  ],
  [
   "Ground",
   "Poison",
   20,
   56
  ],
  [
   "Flying",
   "Electric",
   5,
   57
  ],
  [
   "Flying",
   "Fighting",
   20,
   58
  ],
  [
   "Flying",
   "Bug",
   20,
   59
  ],
  [
   "Flying",
   "Grass",
   20,
   60
  ],
  [
   "Flying",
   "Rock",
   5,
   61
  ],
  [
   "Psychic",
   "Fighting",
   20,
   62
  ],
  [
   "Psychic",
   "Poison",
   20,
   63
  ],
  [
   "Bug",
   "Fire",
   5,
   64
  ],
  [
   "Bug",
   "Grass",
   20,
   65
  ],
  [
   "Bug",
   "Fighting",
   5,
   66
  ],
  [
   "Bug",
   "Flying",
   5,
   67
  ],
  [
   "Bug",
   "Psychic",
   20,
   68
  ],
  [
   "Bug",
   "Ghost",
   5,
   69
  ],
  [
   "Bug",
   "Poison",
   20,
   70
  ],
  [
   "Rock",
   "Fire",
   20,
   71
  ],
  [
   "Rock",
   "Fighting",
   5,
   72
  ],
  [
   "Rock",
   "Ground",
   5,
   73
  ],
  [
   "Rock",
   "Flying",
   20,
   74
  ],
  [
   "Rock",
   "Bug",
   20,
   75
  ],
  [
   "Rock",
   "Ice",
   20,
   76
  ],
  [
   "Ghost",
   "Normal",
   0,
   77
  ],
  [
   "Ghost",
   "Psychic",
   0,
   78
  ],
  [
   "Fire",
   "Dragon",
   5,
   79
  ],
  [
   "Water",
   "Dragon",
   5,
   80
  ],
  [
   "Electric",
   "Dragon",
   5,
   81
  ],
  [
   "Grass",
   "Dragon",
   5,
   82
  ],
  [
   "Ice",
   "Dragon",
   20,
   83
  ],
  [
   "Dragon",
   "Dragon",
   20,
   84
  ]
 ]
}

Each row is [attacking, defending, stored multiplier, line]. Stored multipliers are scaled by 10 (pokered/multiplier-encoding).

Cited by: Pokémon Crystal, Pokémon Red and Blue, Type effectiveness

Multipliers are integers scaled by 10 (SUPER_EFFECTIVE 20, NOT_VERY_EFFECTIVE 05, and NO_EFFECT 00); the table never uses EFFECTIVE (10) or MORE_EFFECTIVE (15). pokered/multiplier-encoding

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

Cited by: Pokémon Crystal, Type effectiveness

AdjustDamageForMoveType applies STAB before any type row: $\mathrm{damage}+\lfloor \mathrm{damage}/2\rfloor$ when the move's type matches either attacker type. pokered/stab

About: Pokémon Red and Blue Same-type attack bonus

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

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

In table order, each TypeEffects row matching the move's type and either defender type sets damage to $\lfloor \mathrm{damage}\times \mathrm{value}/10\rfloor$; 0 marks a miss. pokered/type-step

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

The loop compares each row's defending type with type 1, then type 2 of the defender and applies the row once on either match. Single-type Pokémon store the same type twice (e.g. data/pokemon/base_stats/charmander.asm#L6: db FIRE, FIRE ; type), so they take one step per row. A dual type therefore gets the product of two rows, truncated after each.

Cited by: Pokémon Crystal, Pokémon Red and Blue, Type effectiveness

Under two ½ rows (×¼), 2 or 3 damage truncates to 0 and the move misses; 4 damage gives 1. pokered/zero-damage-miss

Cited by: Type effectiveness

Truncating after each row costs a net-neutral hit damage when its ½ row comes first: Ice against Water/Flying takes 3 to ⌊3 × 5 / 10⌋ = 1, then ⌊1 × 20 / 10⌋ = 2. pokered/truncation-order

Cited by: Type effectiveness

The Red/Blue type chart gives Ghost-type moves no effect on Psychic types. pokered/ghost-psychic

Value: 0 ×

Cited by: Pokémon Red and Blue, Type effectiveness

In Red and Blue, a Saffron Gym trainer's after-battle line contradicts the table: “Psychic #MON fear only ghosts and bugs!” pokered/ghost-psychic-dialogue

Cited by: Type effectiveness

Bulbapedia reports that the Gen 1 Ghost → Psychic ×0 “may have been an error”, citing Nintendo strategy guides, two anime episodes, and the Saffron Gym line. pokered/ghost-psychic-reported-error

A report of intent, not evidence of it. No developer statement has been found (see the gap on the type-effectiveness page).

Cited by: Type effectiveness

Each matching row overwrites the byte wDamageMultipliers, so the text follows the last row: above 10 is “super effective”, below 10 “not very effective”, and a miss reads “doesn't affect” only at 0. pokered/effectiveness-message

{
 "kind": "message",
 "rule": "last-row"
}

Bit 7 of the byte is the STAB flag (constants/battle_constants.asm: BIT_STAB_DAMAGE EQU 7), masked off before the comparison. ExecutePlayerMove seeds the byte with EFFECTIVE (core.asm#L3084-L3085), so a move with no matching row prints nothing.

Cited by: Pokémon Crystal, Pokémon Red and Blue, Type effectiveness

Since the text follows the last row, an Ice move against Water/Flying, net ×1 (½ row at L33, then 2× at L36), prints “It's super effective!”. pokered/message-net-neutral

Cited by: Type effectiveness

A Ground move against Rock/Flying (×0 row at L9, then ×2 at L55) does 0 damage and prints the plain miss text, not “doesn't affect”: the byte holds the last row's 20. pokered/message-immune-miss

Cited by: Type effectiveness

SetDamageEffects moves (Sonic Boom, Seismic Toss, Dragon Rage, Night Shade, Psywave, and Super Fang) jump to the hit test, skipping CalculateDamage and AdjustDamageForMoveType, the only damage routine that reads TypeEffects. pokered/set-damage-skips-chart

Cited by: Type effectiveness

The trainer AI's AIGetTypeEffectiveness stops at the first row matching either defender type, ignoring dual-type products. pokered/ai-first-row

pret marks the routine's neutral seed ld a, $10 as "bug: should be EFFECTIVE (10)"; the caller also compares with $10, so the seed still reads as neutral there.

Cited by: Type effectiveness

The type constants still define BIRD ($06), with a name string, but no TypeEffects row names it. pokered/bird-type

No file under data/pokemon/base_stats/ names BIRD (grep at the pinned commit).

Cited by: Pokémon Red and Blue, Type effectiveness

Type picks the stats: Fire, Water, Grass, Electric, Psychic, Ice, and Dragon (SPECIAL upward) use Special on both sides; the rest use Attack against Defense. pokered/physical-special-by-type

About: Pokémon Red and Blue Damage formula

Cited by: Damage formula, Type effectiveness

In Red and Blue, a damaging move runs CriticalHitTest, CalculateDamage (base formula), AdjustDamageForMoveType (STAB, then type rows), RandomizeDamage, and then MoveHitTest (accuracy). pokered/damage-order

About: Pokémon Red and Blue Damage formula

Cited by: Damage formula, Type effectiveness

CalculateDamage computes $\lfloor \lfloor (\lfloor 2\times \mathrm{Level}/5\rfloor +2)\times \mathrm{Power}\times \mathrm{Attack}/\mathrm{Defense}\rfloor /50\rfloor$, caps it at 997, and adds 2, so the type step receives 2–999. pokered/base-damage

About: Pokémon Red and Blue Damage formula

Critical hits, Reflect/Light Screen, and stat stages change the inputs first (GetDamageVarsForPlayerAttack); this claim doesn't cover them.

Cited by: Damage formula

RandomizeDamage multiplies damage by a random byte, 217–255, and integer-divides by 255, leaving 0 or 1 damage untouched. pokered/random-factor

About: Pokémon Red and Blue Damage formula

[
 217,
 255
]

Cited by: Damage formula, Type effectiveness