If you know anything about GameFreak, you'll know that their use of resources sucks colossal ass. Hell, Gen 2 almost never happened because they ran out of cart space when the game was only half finished and it took the efforts of Iwata to compress it down to the point that Kanto went from a single town to the entire region. They did shit like have multiple copies of the same trainer sprite for each instance of said trainer instead of just having a single instance of the trainer sprite and using that for each instance.

Likewise, the 3D models are the same ones they've been using since the games first went past sprite art which would be fine if they actually put effort into attack animations. But, as stated with their use of trainer sprites, I wouldn't be shocked if GameFreak were so fucking stupid that they couldn't just do something like scale the rigs for snake-type Pokemon for animations. You know, the reason they supposed removed a shit ton of Pokemon and moves. Oh, wait, it was for balance. Balance. From the company that made fucking Calyrex-Shadow. And Zacian-Crowned.