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 multi-strike 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.
Multitype, Zen Mode, Stance Change, Shields Down, Schooling, Disguise, Battle Bond, Power Construct, Comatose, RKS System, As One, Zero to Hero, Commander, Lingering Aroma, and Mummy itself are not affected by Mummy.
Outside of battle
Mummy has no effect outside of battle.