Dragon Ball Z: Season 9, Episode 12

9 - 12: Majin-Buu Transforms

Majin Buu reappears, ready for battle, but rather than continue his fight against Gohan, Buu stages a clever deception to absorb Gotenks and Piccolo. With the wisdom of Piccolo and the power of Super Saiyan Gotenks, Buu transforms into “Super Buu!”