Dragon Ball Z: Saiya-jin Zetsumetsu Keikaku

Synopsis

Dr. Lychee is one of the only survivors of the Tuffles, a race that once lived on Planet Plant before the coming of the Saiyans. The Saiyans not only massacred the entire Tuffle race, but also stole their technology and conquered the planet, renaming it Planet Vegeta in honor of their king. Lychee managed to escape with a capsule and found refuge on the Dark Planet, a world at the end of the universe. Now, his only wish is to eradicate the last remaining Saiyans.

To do this, Dr. Lychee puts devices on Earth that emit Destron Gas and destroy all life, and he sends many monsters to protect this Destron Gas emitters. When Mr. Popo/Bulma finds out that only a few hours are left until the planet's destruction, Goku, Gohan, Vegeta, Future Trunks, and Piccolo rush to destroy the evil devices located around the planet. They manage to destroy all but one that is protected by an impenetrable energy barrier. However, Freeza, Cooler, Turles and Lord Slug appear and engage the heroes in individual fight. It is revealed by King Kai that the villains are Ghost Warriors, and will continually come back to life when killed unless defeated in the same way their lives were originally ended.

(Source: Dragon Ball Wiki)