I call shenanigans. Given Gamera’s calling to defend earth, he’d never risk its total destruction to stop Godzilla, who has a limited beef with a select amount of people and goes away when the beef is squashed. And because the needs of the many outweigh the needs of the few, I’d surmise that Gamera would simply try to drive Godzilla away, but when that didn’t work, he’d die. Of course that’s assuming FW Goji didn’t simply fry him, crush him or dismember him immediately. And we could take it one step further and say, ok, bestest Gamera vs G-Earth, who, I consider to be the Apex Godzilla. Then, interestingly, you have a creature who claims to have access to earth’s mana-banana going up against a creature that basically bent the earth to its will. Dun dun duuuuuuuuuuuun…