Learning a move when that Pokemon only knows hms?

Question

If a Pokemon only knows hm moves, and levels up to a level where it would try to learn a new move, what would happen. What happens if you try to teach that Pokemon a tm?

Comments

Happened with my Empoleon

Answer 1

If a Pokemon only knows hm moves, and levels up to a level where it would try to learn a new move, what would happen.

It would give you the option to learn or not learn it, and when you try to learn it you "Cannot forget" any of the moves.

What happens if you try to teach that Pokemon a tm?

The TM would boot, but the same thing happens as I detailed above. No moves can be forgotten and you would have to cancel the operation.

Source: Experience

Answer 2

You simply wouldn't be able to teach it that move. It wouldn't let you delete any of the HM moves, so your only option is to cancel your Pokemon learning the move.

This doesn't mean the Pokemon loses the ability to learn that move though; if you take a Heart Scale to the move relearner in Dendemille Town they will give you a list of your Pokemon's level up moves for you to teach to your Pokemon. Of course, make sure you've deleted one of the HM moves before you talk to the move relearner.