Godzilla vs. Megalon

You know who Godzilla is. Megalon is a huge cockroach-like beast. Godzilla has been a good guy since 1961, so Megalon is consigned to the villain's role. Godzilla is evidently in seclusion, so the people of Tokyo build a robot to seek out the big lizard (wouldn't a phone call have sufficed?) Don't miss the Gigan, the creature with a buzzsaw in its abdomen.