The Clone King is the semi-final Boss, and, hence his name, is the king of the Clone Troop. He is stronger than any Clone Troopers except of his true self, Clarx. He is heavily based on the Legendary Pokémon, Groudon. The shadow bits around him can indicate that he have the power of darkness.
Meeting him at World 8 Boss Stage will be hard, because his weight will OHKO you if he fall on you, but he jump so high that he will get stuck, so you can stomp him. He takes 5 hits, and after the 2nd hit, he roars and start to spit fireballs. It don't OHKO you but these will chase you if it is nearby at you. After the 3rd hit, he roars again and throw darkballs, harder to dodge does to it size but do not chase you and a bit slower too. After the 4th hit, he become mad and roars very hard. After the 5th hit, he lay down, pretend to get hurt badly, then make a very evil laugh, and make his quote, then he tranform into Clarx.