Fighters are very strong against rock types. But you're not seeing that here right now. The little impressionable Larvitar saw 'Top balancing on his head, preparing for the battle and attempted to mimic the act. Only failing the ability to keep it's balance while doing so. After three attempts, Larvitar was beginning to feel discouraged, but decided to give it one more go. While up on the point of it's head, the pokemon began to wobble and lose it's balance, but only to be caught by the hand of the awaiting hitmontop who had been watching this whole time. With 'Top's aid, the Larvitar manage to achieve his goal on mimic his "opponent".

And thus, hitmontop found a new friend that day.

(sorry, I was feeling Not-porn-ish the day I drew this)