what does ability mummy do?

Question

Instead of making other pokemon into mummy when it is hit by physical attack

Answer 1

Like you said turns your opponents ability into mummy.

>Overwriting the Pokémon's previous Ability. The affected Pokémon's Ability returns to normal when they are returned to their Poké Ball.

[**Source**][1]

I love Weird things ¯(°_o)/¯
[1]: http://bulbapedia.bulbagarden.net/wiki/Mummy_(ability)