Generation Iv
Aftermath
Damages the foe landing the finishing hit.
Detailed Effect
When this Pokémon is knocked out by a move that makes contact, the move's user takes 1/4 its maximum HP in damage.
Pokémon With Aftermath
11 canonical Pokémon forms can have this Ability.

Drifloon
Drifblim
Stunky
Skuntank
Voltorb 
Electrode
Trubbish
Garbodor
Garbodor Gmax
Hisuian Voltorb
Hisuian Electrode