Invincible Superman Zanbot 3

Kappei is your normal run of the mill delinquent lad, riding motorcycles and trying to gain leadership of a gang. When fighting with a rival, they are both attacked by a strange creature! Fleeing to his Grandfather's nearby sea rig, Kappei is knocked into the water and is rescued by a giant spaceship piloted by his grandparents. Before he can figure out what is going on, he finds himself in the mighty Zam-bird, fighting against the monster that attacked him - a mecha-boost of the planet-destroying Gaizok! Kappei isn't the only one in his family who ends up with a giant robot, though; his cousin Uchuta pilots the Zambull and Keiko pilots the Zambase. Together, the three of them can transform into the Invincible Superman Zambot 3!