When a Pokémon with Mummy is hit by a contact move, the attacker's Ability is changed to Mummy. The attacker regains its original Ability once it is switched out, faints, or the battle ends.
If a Pokémon with this Ability is hit by a multistrike move that makes contact (such as Fury Swipes), the attacking Pokémon's Ability will become Mummy after the first strike.
If a Pokémon with Rock Head uses a recoil contact move on a Pokémon with Mummy, its Ability will become Mummy, then subsequently it will take recoil damage. If a Pokémon with Parental Bond uses a contact move on a Pokémon with Mummy, the Pokémon's Ability will become Mummy after the first strike, then the current move will continue to strike a second time regardless. If a Pokémon with Skill Link uses a multistrike contact move on a Pokémon with Mummy, the Pokémon's Ability will become Mummy after the first strike, then the current move will continue to strike the maximum number of times regardless.
Changes the Ability of the Pokémon that hit it with a direct attack to Mummy.* When the Pokémon is hit with a direct attack like Tackle or Scratch, the attacker's Ability becomes Mummy!*
When the Pokémon is hit with a contact move like Vine Whip or Iron Tail, the attacker's Ability becomes Mummy!
In the manga
Pokémon Adventures
Gorm's Cofagrigus is revealed to have Mummy as his Ability.
Trivia
The effect of this Ability may be a reference to the Japanese expression ミイラ取りがミイラになる (mīra-tori ga mīra ni naru), meaning "the mummy-taker becomes the mummy".
