Hitmonchan first appeared when he was sent out to battle Misty's Politoed, but was easily defeated. He was later used again during the battle against Misty for the Cerulean Gym, only this time against her Staryu. During the battle, he almost drowned. As Staryu swam up to help it, he woke up and attacked Staryu by punching it to a nearby rock. But despite Staryu being unable to battle, Nurse Joy declared that Hitmonchan's sneak attack was illegal and gave the win to Staryu instead.
None of Hitomonchan's moves are known.