Vegetto is a fusion of Goku and Vegeta fused when each wore one of Rou Dai-Kaioshin's special earrings on opposite ears. Vegetto was able to stand up to Buu, but allowed Buu to absorb him to rescue their comrades still inside of Buu's body. And that effected the permanent fusion and when they were spit back out the fusion was cancelled.
Gogeta is the fusion result of Goku and Vegeta. In Dragonball GT, Gogeta was formed again when SS 4 Goku fused with SS 4 Vegeta. SS 4 Gogeta is the most powerful character in the Dragonball series. He fought against Evil Shenlong in this form.
He is the fusion result of SS 4 Goku and SS 4 Vegeta. He is the strongest and most powerful character in all of the Dragonball series. He has red hair, red eye brows, his eyes are still the same color, and is covered in red fur except his face and chest. He first appears in Dragon Ball GT in a fight against Li Shenlong. SS 4 Gogeta overpowered Li Shenlong but the fusion wore off before he could destroy him.
Gotenks is the fusion result of Goten and Trunks. Gotenks has an attitude like he could take on anyone. This is mainly due to his age and immaturity. He has two very powerful and unique attacks, Super Ghost Kamikaze Attack and the Shine Shine Missle. He has many other attacks that aren't as effective. He is also the second, and last person to reach the Super Saiyan 3 form. He has an incredible amount of strength and power, and he almost defeated Buu, but the fusion wore off before he could finish him.
