Godzilla vs. Gigan (1972)
"Chikyû kogeki meirei: Gojira tai Gaigan" (original title)

From Earth's pollution a new monster is spawned. Hedorah, the smog monster, destroys Japan and fights Godzilla while spewing his poisonous gas to further the damage.

Apelike aliens build a robotic Godzilla to destroy Japan, and the true Godzilla may not be powerful enough to destroy it.

Godzilla comes to the rescue when an alien race rebuilds Mechagodzilla to destroy Earth's cities. A traitorous scientist gives them a second weapon: Titanosaurus.

The undersea nation of Seatopia sends the gigantic Megalon to destroy the world above - and it's up to Godzilla and a size-shifting robot, Jet Jaguar, to defeat him.

A young man steals a boat to find his brother, but he and his shipmates become shipwrecked on a mysterious island inhabited by a giant sea monster and a slumbering Godzilla.

Female aliens take control of Earth's monsters and begin using them to destroy the human race.

Time travelers use Godzilla in their scheme to destroy Japan to prevent the country's future economic reign.

The United Nations assembles the ultimate weapon to defeat Godzilla, while scientists discover a fresh pteranodon egg on a remote Japanese island.

In the midst of another rampage by Godzilla, Mothra emerges to save the human race from Battra.

Japan creates an artificial black hole device to trap Godzilla forever, but a test of the device creates new foes for Godzilla, car-sized dragonflies called meganula and their queen, Megaguirus.

Godzilla is threatened by two new forces: Mogera - another UN built machine; and Space Godzilla - a beast spawned from Godzilla's particles in space.

After a meteorite unleashes a three-headed beast upon Tokyo, Mothra tries to unite with Godzilla and Rodan to battle the extraterrestrial threat.