Copycat is a human with the ability to shapeshift into anyone he sees. He appears in the Copycat saga in Dragon Ball Infinity. He debuted in the episode "One Hercule Was Bad Enough..."
Just like all other humans, Copycat thinks Mr. Satan is the universe's strongest, so he turned into Hercule. But he soon learned that Goku is the strongest, so he turned into Goku. Since Goku has a high power level, Copycat was nearly unbeatable.
Masenko-learned when he transformed into Piccolo
Kamehameha-Learned from Goku