Genki is a half-saiyan and half-Human who was raised on earth when he knew that he started to train himself to become the strongest on the earth. He can transform into a super saiyan and Super saiyan 2 and when he met Goku he learned to become Super Saiyan 3 but not for long, then by training he mastered Super Saiyan 4.
normal
Super Saiyan
Super Saiyan 2
Super Saiyan 3
Super Saiyan 4