Godzilla vs. Megalon

In the film, the undersea civilization Seatopia has been heavily affected by nuclear testing conducted by the surface nations of the world. Naturally upset by this, they unleash their civilization's god, Megalon, to the surface to destroy the world. Agents of Seatopia attempt to steal the newly-constructed human-sized robot, Jet Jaguar, which they use to guide and direct Megalon. They also capture the robot's inventor, Goro Ibuki, his kid brother Rokuro and their friend Hiroshi Jinkawa. After Jet Jaguar is used by the Seatopians to lure Megalon to Tokyo and the Japan Self Defense Forces fail to defeat it, Goro manages to regain control, and sends Jet Jaguar to Monster Island to bring Godzilla to fight Megalon. An extended fight scene then takes place, with Godzilla and Jet Jaguar, the latter newly giant-sized and self-directed, fighting Megalon and Gigan in the hills outside Tokyo. The film ends with Megalon and Gigan defeated, Godzilla returning to Monster Island, and Jet Jaguar returning to his previous, human-sized state.

I think it is a very odd film it has lots of stock fottage, has a monster that looks like a giant cockroach (Megalon), and Bugs teaming up with human-like creatures