Just wondering for a doubles strategy...
The user transforms into a copy of the target right down to having the same move set. Transform copies the target Pokémon's Ability Alters the user’s cells to copy the target.
It will copy the target's ability, therefore not retaining its own.
Source
Hopefully, I've Helped.
Ditto copies everything about the opponent other than HP. So if you Transform into another Pokémon the you will lose Limber/Imposter and gain the ability of the Pokémon you copied.