GIGANTAMAX BUTTERFREE

G-Charizard may have failed to reference any Toho kaiju, but I'm sure the existence of Mothra is why they chose to give Butterfree a Giganta-form. It's almost exclusively the wings that change, with only minor alteration to its antennae, but hey, whatever, it works. It looks nice. I don't mind it. Its said that "crystallized gigantamax energy" makes up the scales on its wings, which are now blindingly luminous and extremely toxic.

I will take this opportunity to say that "giant monster" Pokemon forms were actually the central gimmick of my own hypothetical fan-region, though mine were actual evolutions rather than three-turn transformations, and mine, as a rule, were available only to un-evolved Pokemon, the very first of which was to be a terrifying, dragon-like Caterpie.