O's Ambipom

Ash caught Aipom in the Battle Frontier arc, but it had appeared in a few previous episodes, causing Ash trouble by stealing his hat. This eventually provoked Ash into battling and catching Aipom during the Grand Festival. However Aipom still continued to steal Ash's hat whenever it seemed jealous of Pikachu's bond with Ash. Later, in the Battle Dimension series (season 11), after being advised by their friend Zoey, Ash traded his Aipom to Dawn for her Buizel, as Aipom loved contests, while Buizel likes to win but never wins. Soon after Dawn recieved Aipom, she taught it Double Hit, causing it to evolve in that same episode into Ambipom.