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 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.
Open question: what happens if a Pokemon has Skill Link and uses Triple Axel on an opponent with Mummy? Does it skip accuracy checks on the second and third hits?
Relevant Code Points
Function 0x0225708C needs to support a new branch for Mummy. There should be an interrupting subscript which triggers and announces the ability's activation, similar to Rough Skin.
Documentation
https://bulbapedia.bulbagarden.net/wiki/Mummy_(Ability)
Open question: what happens if a Pokemon has Skill Link and uses Triple Axel on an opponent with Mummy? Does it skip accuracy checks on the second and third hits?
Relevant Code Points
Function
0x0225708Cneeds to support a new branch for Mummy. There should be an interrupting subscript which triggers and announces the ability's activation, similar to Rough Skin.