Godzilla vs. Hedorah (1971)
An ever evolving alien life form from the Dark Gaseous Nebula arrives to consume rampant pollution Spewing mists of sulfuric acid and corrosive sludge, neither humanity or Godzilla may be able to defeat this toxic menace
Godzilla vs. Megalon (1973)
An inventor creates a humanoid robot named Jet Jaguar that is seized by the undersea nation of Seatopia Using Jet Jaguar as a guide, the Seatopians send Megalon as vengeance for the nuclear tests that have devastated their society