Gogeta

Kakarot + Vegeta = Gogeta. Since Vegeta can only go to level 2 Gogeta can only go level 2. After Bulma uses the device on Vegeta they fuse in Dagonball GT to form Level 4 Gogeta. Gogeta wears a orange and black vest with baggy white pants.

Gotenks

Chibi Trunks + Goten = Gotenks and they learn a new attack, Ghost Kamakazi. Gotenks grows abit in height and wears a orange/yellow and blue vest with baggy white pants. He has black hair with purple hair on each side of his head. Trunks and Goten only get to level 2 but Gotenks can go SSJ level 3. The reason for that is unknown.

Vegetto

But with the special earrings Kakarot + Vegeta (Kakarot with one ear ring on the left ear, Vegeta with the other ear ring on his right ear) They then permanently fuse into Vegetto. But they also somehow un-fuse from being Vegetto inside Majin Buu's stomach. The reason is unknown. Vegetto is the strongest of the all the characters in DBZ/GT. He wears orange shirt with blue overall type things as seen in the picture.