A failed fusion can only occur when fusing using the Fusion Dance in an incorrect way. Many of the fusions in the series have been performed incorrectly, leading to a failed fusion. There are examples of failed fusions from Dragon Ball Z, from movies, and from video games.
Failed versions of Gotenks
Goten and Trunks achieve this form when the Fusion Dance goes wrong, probably because Trunks stretches his finger at the moment he and Goten say, "-sion!". The result is a fat version of Gotenks. He tries to run but tires very quickly. For a moment, Krillin and Yamcha think that the fusion has succeeded and that Gotenks has to be fat to regulate his power, similarly to Majin Buu. However, they soon change their minds when they see that fat Gotenks becomes winded after a brief and slow run. Fat Gotenks is also seen in Dragon Ball: The Return of Son Goku and Friends!, Goten and Trunks as Fat Gotenks say that they did not practice the fusion dance for a long time, and then they defuse. He is a playable character in Dragon Ball Heroes, but in other video games, he can not do any special attacks and is already tired after a few kicks and punches. In the case of Dragon Ball Z: Buu's Fury, neither he nor the skinny variant can even move, and defuse automatically after a few seconds so that a successful fusion can be performed. Fat Gotenks is playable in Dragon Ball Z: Dokkan Battle, under the name Gotenks (Failure) A.
Goten and Trunks achieve this form of Gotenks when the Fusion Dance goes wrong for a second time. The failure is due to a lack of coordination, as when Goten and Trunks say "HAAH," their fingers do not meet. Skinny Gotenks can barely stand on his feet without getting tired, and he coughs a lot as well. Comically, after seeing this form of Gotenks, Chi-Chi exclaims "Oh no! I can't love that!" to which Master Roshi asks "Why not? He's my age!", Krillin responds with "No...older!" Yamcha says, "His ribs are showing! We need to beef him up or something." Skinny Gotenks is playable in Dragon Ball Z: Dokkan Battle, under the name Gotenks (Failure) B.
Veku (ベクウ Bekū) is the failed attempt at Goku and Vegeta fusing into Gogeta. He is a fat and embarrassingly weak fusion fighter, named by South Kai in Dragon Ball Z: Fusion Reborn from Vegeta and Goku.
In this form, Veku is nowhere near as strong as he would like to be, and his ki and stamina are extremely limited. He does not perform any special ki attacks due to these limitations, as well as being unable to punch or kick well due to his fat body. Instead, all he is capable of doing is pass gas and escape battle with his surprisingly fast Rabbit Feet Technique. Like most fusions, there is a 30-minute time limit before he defuses back into Goku and Vegeta.
Veku first appears in Fusion Reborn, in Goku and Vegeta's attempt to beat Super Janemba. King Kai blames Vegeta for the blunder, claiming that Vegeta didn't extend his index finger, which led to the fusion failure. Luckily, Veku is able to take Janemba's blows and outmaneuver him until the 30 minutes of fusion are finished, allowing Goku and Vegeta a successful opportunity to re-fuse, this time successfully into the deadly Gogeta, who easily eradicates Janemba.
In Dragon Ball Super: Broly, Goku and Vegeta fail twice to properly perform the Fusion Dance, resulting in failed fusion Gogeta making two appearances: as Veku, firstly due to Goku's finger slipping below Vegeta's and the second time as an extremely skinny Veku due to Goku being tilted at a 45-degree angle while Vegeta is tilted at a 60-degree angle. On their third try, Goku and Vegeta manage to successfully form Gogeta and leave to confront Broly.
Before Broly, concept arts for a skinny Gogeta were originally shown in Daizenshuu 6, in the Fusion Reborn area, but the character was not included in the final version of the movie. A skinny Gogeta card exists in Dragon Ball Carddass. Skinny Gogeta is also in Dragon Ball Z: Buu's Fury, appearing when the player fails to do a proper fusion.
- Video Game Appearances
Veku is a playable character in Dragon Ball Heroes, Dragon Ball Z: Budokai 3, Dragon Ball Z: Dokkan Battle, and Super Dragon Ball Heroes: World Mission. In Dragon Ball Xenoverse 2, he appears as one of five chibi avatars that can hover around the Future Warrior and comes in his base, Super Saiyan and Super Saiyan Blue forms.
- Techniques and Special Abilities
- Kamehameha – Veku can use this in Dragon Ball Heroes and Dokkan Battle.
- Rabbit Feet Technique – A running away technique used by Veku to flee from Super Janemba.
This form of Tiencha arrives in Dragon Ball Z: Budokai 2, when Yamcha and Tien Shinhan stretch their hands when they say "HAAH" in the last stage of the Fusion Dance, a costly mistake. In this form, Tiencha can still fly but can't do any special attacks. He can only use punches, kicks, and simple ki attacks, and even these cost him a large portion of his energy. After a combo attack, he coughs, and if he tries a special attack like the Dodohameha, he again coughs, causing the attack to fail.
- Daizenshuu 6, 1995