Liquid Ooze

 is a Pokémon ability introduced in the third generation. It causes damage to an opponent attempting to drain the Pokémon.

Description
Whenever this Pokémon is attacked by one of the below moves, the opposing Pokémon loses the HP that they would have gained. This includes the boost from Big Root. The Pokémon with this ability does not take any damage.

Affected Moves

 * Absorb
 * Drain Punch
 * Draining Kiss
 * Dream Eater (After Gen V)
 * Giga Drain
 * Horn Leech
 * Leech Life
 * Leech Seed
 * Mega Drain
 * Oblivion Wing
 * Parabolic Charge
 * Strength Sap

Pokémon with Ability

 * Tentacool
 * Tentacruel
 * Gulpin
 * Swalot

Trivia

 * The ability is exclusive to Poison types.