Two examples from other Pokemon:
Pachirisu hits the opponent with its tail.
Stoutland jumps high into the air above the opponent and brings its front paws down as it falls, slamming the opponent into the ground. The move is most powerful when Stoutland has used all of its other moves.
It is just a damaging move so you would have to create an action that is applicable to Munchlax. Although, since we don't use PP in this RP, I'm not sure how the requirements for the move will be made.