Ravenous

Whenever this Pokémon uses a Jaw-based (biting) move, it regains HP equal to 1/4 the damage dealt.

If this Pokémon is holding a Big Root, the HP regained increases to 13/40 the damage dealt.

If the target has Liquid Ooze, this Pokémon loses HP equal to 1/4 (or 13/40 with Big Root) the damage dealt instead.

If the move used is Vampire Fang, Vampire Fang will drain (or lose, in the case of Liquid Ooze) 5/8 the damage dealt instead of its usual 1/2.