Space Runaway Ideon

Humanity's pursuit of knowledge leads them to the planet Solo, where they find mysterious remains of a long dead alien civilization, including the 3 part super robot 'Ideon', and a powerful warship. Using these, the Earthlings sent to investigate the ruins defend themselves in their constant conflicts against powerful aliens called the Buff Clan, who are in pursuit of 'Id', the mysterious energy that powers the Ideon.

Synopsis from Anime News Network