Vegetto wasn't really a person seen a lot! I think he was only in movies. This is the fusion of Goku and Vegeta with the kaioshin earrings on. Vegetto was absorbed by Buu. Vegeta then took his earring off, and crushed it. Goku did the same. That was basically the end of Vegetto!
(more info to come)
Vegetto and Gogeta... info from JRice80S
Gogeta is a lot weaker than Vegetto because when performing the Fusion Dance (with out the earrings) the 2 people have to be about the same power level so Goku lowered his power level down to match Vegeta's which makes this a bit weaker fighter (yet still a good one). Yet Vegetto when u have the earrings you don't have to be at the same power level which makes Vegetto a lot stronger than Gogeta.
People have emailed me saying that Gogeta is stronger than Vegetto. And they are correct. But they are only correct in the term that Gogeta went Super Saiyan 4 and Vegetto didn't. That is one of the ways Gogeta become really powerful.
Gotenks is the fusion of Goten and Trunks. They used the fusion dance for this and created Gotenks. His most powerful stage was Super Saiyan 3.
Gotenks was first seen in the Buu saga and turned super saiyan 3 but was still absorbed by Buu. Gotenks never really shows up again after that but that seems to be because after kid Buu blows up the earth Goten and Trunks never or hardly ever hang out any more. I sat that's because after that Goten gets a girlfriend and Trunks hangs out with Pan, Gell, and kid Goku in search for the black star dragon balls
Gogeta is the fusion of Vegeta and Goku. They used the fusion dance for this and created Gogeta!
I thank Ando501 for this information... Gogeta was first seen in movie 12. Ssj3 Goku was unable to beat the evil entity Janemba, and neither was Vegeta. They were forced to fuse, the first time they got it wrong and ended up with a fat version of Gogeta, but the second time they did it right and formed the perfect Gogeta. He easily defeated Janemba. The next time we see Gogeta is against Evil Shenlong in GT. Gogeta goes ssj4 also. When he goes ssj4 his hair goes red, and his eyes red also. I think he gets a little fur on him also. Gogeta also isn't as strong as Vegetto is. Vegetto is a perfect fusion were neither warrior had to be at or near the same power level (because of the earrings). When forming Gogeta, Goku and Vegeta had to be at the same Power level. That meant Goku had to lower his to match Vegeta. That would result in a less powerful (but still extremely strong) fighter.
If anything is wrong with Ando's saying about Gogeta, say so! I think he's got it all on the knob!