Well, I never implied it was the *correct* thing to do (as developer myself, it makes me cringe), I'm just stating what is the reality however.
I'm unsure if they're entire isolated models, but Dinamax definitely has its own dedicated animations, even though they're essentially reskinned versions of base ones, which is why "freshly imported" hacked pokemon made the game crash or had to use placeholder animations for Dynamaxing.
Something Something 7 Lilie models
Unrelated: I do know kids that behave like the stereotype that you hate
Pikachu315111 . Luckily only a minority, most of the kids I know or run into are, you know, normal, but I can guarantee you there is a small yet noticeable part of kids that will indeed drop games when they run into anything they can't bruteforce.