It is pretty simple, and I'm not sure if this has been mentioned before, but here goes...
- Start the fight with a Pokemon with the ability Mummy (ex. Cofagrigus)
- Have Mummy pass on to the opponent.
- Once Cofagrigus faints (or you swithch to Slaking), Mummy passes on. >
My main question is, does Mummy get rid of you normal ability and replace it with Mummy, or does Mummy become a second ability like Air Balloon does?