[True indeed, Farron sisters are tough stuff. He steps a bit closer and kneels near where Mog's hopping about]

There're a couple of tricks to learning new moves, at least. If you send your Hoppip in at the start of a battle and swap to someone else, she'll still get experience. With levels, she can learn another move.

If you don't want to do that, there's also move tutors.