Guts

Guts raises the ability-bearer's Attack by 50% when inflicted by a major status ailment (poison, burn, paralysis, freeze or sleep). If burnt, the Pokémon does not suffer the usual drop in Attack. All other effects of the status condition remain, e.g. losing HP each turn (poison, burn), speed drop (paralysis) or being unable to attack (paralysis, freeze, sleep).

Game descriptions

Ruby, Sapphire, FireRed, LeafGreen, Emerald:Ups ATTACK if suffering.
Diamond, Pearl, Platinum, HeartGold, SoulSilver:Boosts Attack if there is a status problem.
Black, White, Black 2, White 2:Boosts Attack if there is a status problem.
X, Y, O.Ruby, A.Sapphire:Boosts the Attack stat if the Pokémon has a status condition.
Sun, Moon, Ultra Sun, Ultra Moon:It’s so gutsy that having a status condition boosts the Pokémon’s Attack stat.
Sword, Shield, B.Diamond, S.Pearl:It’s so gutsy that having a status condition boosts the Pokémon’s Attack stat.
Scarlet, Violet:It’s so gutsy that having a status condition boosts the Pokémon’s Attack stat.

Guts

Game descriptions

Pokémon with this ability (24)