Ok, but no, that 's not how I think they deal with rolling/spinning. Sonic's spin attack was a "technique" not because hedgehogs don't roll by default, but because thanks to his speed his rolling becomes a weapon, he's like a living chainsaw. More than Amy can or cannot spin, thing here is she wouldn't do it at supersonic speeds, less so if she's both young and untrained, but at some point she got a magical hammer and learned to use that instead in a better or worse way. Now yes, Tails and Ray spinning is stupid because they're so fluffy; even if rolling wasn't weird for foxes or squirrels, they have no natural weapon. It makes a lot more sense for Tails that said tails are dangerous during his propeller flight for the same reasons those tails allow him to somehow follow Sonic's speed; if we're gonna have impossible natural skills, better exploit the signature ones instead of cloning what the main character did first. But now that we are with impossible signature skills, fluffy animals rolling still make more sense than an echidna gliding, and we don't complain about that, do we? It must be some acquired chaos power, right? There's no other explanation for that. So yes, you can say real world species are not a factor in deciding this stuff, but Mighty is an armadillo with a hard shell and amradillos also roll in real life, so being that hard excuses him from becoming a wrecking ball, and Ray glides because he is, well, a flying squirrel; are you sure real world species is not a factor? Truth is, only convenience and cool design are factors. I always found brutal they removed back quills from Amy, brutal as in they mutilated her, but she had to look more like a girl and less like a Sonic, yes? Because there are a Sonic MkII (Shadow) and a Sonic MkIII (Silver) who retain enough of a hedgehog look, much like all the mecha doppelgangers. In all those cases, they're reinventing Sonic in some way, but that's not the case with Amy, so they demote her from being a hedgehog or make her a hedgehog again when they need to. Convenience and cool design, as I said. I mixed a couple of things here to both show there are explanations of all kinds for things you're asking them for, but also that this inconsistency and constant change of mind is deliberate and obeys to nothing but the development of each individual project as much as continuity does, so yes, Amy now rolls, now she doesn't, and only hedgehogs grind rails, and only male hedgehogs can become super in modern games.