Movies like Dragon Ball Z Gaiden: Saiya-jin Zetsumetsu Keikaku

Dr. Raichi, a survivor of the Tuffle race that was eliminated from Planet Vegeta by the Saiyans, is trying to take revenge on the surviving Saiyans by killing them and Earth's population. Goku, Gohan, Piccolo, Trunks, and Vegeta must find and destroy generators emitting deadly Destron Gas before all life on Earth is extinguished, then find Raichi and stop him.