The word 'FUSION' comes from the word 'FUSE', which it means to join or to connect together. In DragonBall, it means exactly that, to let two fighters to join together into a single, more powerful and a more dominate fighter.
In this section, we will discuss the different fusion methods, By using successful fusion characters such as Gogeta, Gotenks as examples to explain to you how fusion works and the impact it created on the 'fused' characters.
A powerful and permanent fusion created by using Kaioshin's earrings. Each of the two fighters wears one earring at the opposite ears then a fusion will be formed. This fusion is stronger than any other fusion as it cannot be separated unless for an unexpected accident/case (i.e. When Buu ate Vegetto, and for some reason they got seperated while in Buu's body). Hence, this newly fused character is likely to stayed fused for the rest of his/her lifetime. This method is also the best because the it guarantees the most optimal result for the newly fused character.
Well, how about the costume? What is the newly fused character wearing after fusion? The costume the fused character wears is a combination of the two fighters' cloths and the physical appearance is the assemble of the two fighters too. Unlike the Fusion Dance method, the two fighters that fused using the earrings don't have to have similar power level or size because as long as they both wear the potara earrings their bodies will be attracted by each other (like a magnet) and will combine no matter what.
This technique is taught to Son Gokou by Metamora in the afterlife (approximately between the end of cell game and when Gohan started school). The two fighters have to perform a complicated dance while saying the word 'FUSION'. All the moves in this dance have to be performed properly and accurately or else a deformed fusion will be formed (i.e. Veku, a fat Gogeta, Trunkten, a fat Getenks, or Gotrunks, a skinny Gotenks). It takes practice to get the dance right, and it is not easy.
The fusion formed using this dance can only last for 30 minutes. If they wish to fuse again after that, they need to wait for an hour before performing the fusion dance and fuse again. The time limit for the fusioned character will be shorter if the fusion is in Super Saiyan-Jin 3 stage, since it takes a lot more power and strength when the fusion is formed. The costume the fusion wears is a traditional costume of Planet Vegeta. All the fighters that fused using the dance must have a fuse partner who has similar power lever, weight, height etc. as the fighter himself or else they will not fuse. All fused characters are usually cocky!
It is also known as Yuugou Fusion. This fusion can only be used between two Namekians. The two Namekians will combine their enegry/power into one and the power of the new fusion will dramatically go up. The Namek who is absorbing the other Namek (hence, the new fusion will look like this Namek), must place his hand in the other Namek's chest.
FAMOUS FUSED CHARACTERS
Fusion of Gokou and Vegeta using the Potara earrings. Vegeta is the dominant character here. The technique used here is Potara Fushion therefore at the same SSJ stage Vegetto is physically stronger than Gogeta. This fusion supposes to be permanent however Gokou and Vegeta got separated after Buu ate Vegetto.
Fusion of Gokou and Vegeta using the fusion dance. Gokou is the dominant character here. Gogeta is a quick minded and fast character (maybe he has to act fast since this fusion can only last for 30 minutes).
A rather playful character formed by chibi Trunks and chibi Goten. Gotenks is the first fusion character formed to fight Buu. Trunks and Goten tried many fusion dance attempts before this powerful yet naive character is formed.
LIST OF ALL FUSED CHARACTERS
Gokou + Vegeta = Gogeta (Fusion Dance)
Gokou + Vegeta = Vegetto (Potara Earrings)
Gokou + Vegeta = Veku - Fat Gogeta (Fusion Dance)
Trunks + Goten = Gotenks (Fusion Dance)
Evil Andriod #17 + original Android #17 = Super #17
Android #13 + Android #14 + Android #15 = Ultimate Android #13 (Absorbed No 14 and 15's CPU)
Majin Buu + Vegeta = Majin Vegeta
Kaio-shin + Kibit = Kaio-Kibit (Potara Earrings)
Piccolo + Nail = Picconail (Namekian Fusion)
Piccolo Daimaou + Kami-Sama = Kamicolo - or still referred to as Piccolo (Namekian Fusion)