>>38930590hacker's memory had 341 playable digimon. that's more than any regional dex except for kalos. they still managed to have pokemon stadium-tier normal attack animations and kino special attack animations for every single one of them.
additionally, digimon's devs had a far smaller budget, the constraints of the vita's hardware, and digimon tend to have more detailed designs on average that take more effort to model.
there is no excuse for game freak, none.