Dragon Ball Z: Lord Slug

Gohan and Piccolo are interrupted from their peaceful moment by a powerful entity approaching Earth, which is revealed to be a small planet on a collision course. Goku and Kuririn attempt to use a Kamehameha to change the planet's path, but their attack fails, and they're blown away. The planet, after narrowly avoiding Earth's surface, explodes, only to reveal a castle-like structure emerging from its remains. A large army, declaring the planet now under Slug's control, invades Earth, and Gohan loses his Dragon Ball, allowing Slug to take it. Slug then uses the Dragon Radar to locate the other Dragon Balls and gathers them to wish for his youth back, granting him immense power.