Vegeta does not appear in the movie “Dragon Ball Z: Fusion Reborn” until the latter part of the film. He assists Goku in the fight against the movie’s antagonist, Janemba, by performing the Fusion Dance to become Gogeta and defeat the villain.
In “Dragon Ball Z: Fusion Reborn,” which is the 12th Dragon Ball Z movie, the story begins with an accident in the Other World that causes the dead to return to life. Goku is already in the Other World after his death and is dealing with the consequences of the accident. Vegeta, who is also deceased at this point in the series, eventually shows up to aid in the battle against Janemba, a powerful demon that has caused the disruption.
Janemba’s reality-warping powers and immense strength prove to be too much for Goku to handle alone. After realizing the dire situation, Goku convinces Vegeta to perform the Fusion Dance with him. Despite Vegeta’s initial reluctance and pride, he agrees to fuse with Goku, resulting in the creation of Gogeta. Gogeta possesses incredible power and speed, and he is able to effortlessly overpower Janemba, ultimately defeating him with the Stardust Breaker attack, which purifies Janemba’s evil energy and restores order to the Other World.
The fusion of Goku and Vegeta into Gogeta is a significant moment in the movie, showcasing the combined might of two of the series’ most powerful characters and their ability to set aside differences for the greater good. Vegeta’s participation in the Fusion Dance is a testament to his character development, as he puts aside his rivalry with Goku to save the universe from destruction.