this morning, I discovered that this kid in Godzilla Against Mechagodzilla is meant to be the kid from Hamtaro
so while GxM doesn't exist in any prior Godzilla timeline, it does exist in the Hamtaro universe, which to me implies that the sentient hamsters are some form of mutation as well, possibly irradiated by-
Godzilla (1954) - Ishiro Honda // Journal Excerpt, July First - twinnedpeaks // Godzilla Minus One (2023) - Takashi Yamazaki // papayajuan2019 // Godzilla (1954) - Ishiro Honda // Godzilla Minus One (2023) - Takashi Yamazaki // The Angriest Dog In The World - David Lynch // Ishiro Honda on Rodan (1956) // Godzilla (1954) - Ishiro Honda