When a Pokémon with Innards Out faints, it deals damage to the opponent equal to the amount of HP it had remaining before the final blow.
Innards Out
When the Pokémon is knocked out, it damages its attacker by the amount equal to the HP it had left before it was hit.
Pokémon with the Innards Out ability
#71
Mega Victreebel
grass
poison
HP: 80 Atk: 125 Def: 85
Sp.Atk: 135 Sp.Def: 95 Speed: 70
Total: 590
#771
Pyukumuku
water
HP: 55 Atk: 60 Def: 130
Sp.Atk: 30 Sp.Def: 130 Speed: 5
Total: 410