Space Gyaos and Guiron are great (and the brain-eating space ladies, of course), but the film wouldn’t work as well as it does without Gamera being at the top of his game. Yes, it’s the goofy Gamera, who does Gymkata at one point on a convenient crossbar. However, the Gamera movies, even the comparatively serious first black and white one, were always clearly aimed at kids, so it’s not as weird as suddenly seeing Gojira dances jigs or whatnot.
There’s also the Tremendous Terrapin’s neato introduction in space (with the smoke from his jets floating suspiciously upwards), several uses of the marvelous Gamera theme song, and best of all, numerous examples of Spinning Flying Gamera, which pretty much everyone acknowledged to be his ultimate form. If I have one small critique about the ’90s Gamera films, as superb as they are, it’s that we don’t get nearly enough Spinning Gamera.