Aftermath (ability)

Effect

If an attacker faints a Pokémon with Aftermath using a contact move, the attacker will lose 14 of their maximum HP.

Game descriptions

Diamond​/​Pearl
Platinum
HeartGold​/​SoulSilver
Damages the foe landing the finishing hit.
Black​/​White
Black 2​/​White 2
Damages the attacker landing the finishing hit.
X​/​Y
O.Ruby​/​A.Sapphire
Damages the attacker landing the finishing hit.
Sun​/​Moon
Ultra Sun​/​Ultra Moon
Damages the attacker if it contacts the Pokémon with a finishing hit.

Pokémon with Aftermath

Aftermath as a hidden ability