AI image generation wasn't good enough in early 2022 to generate game assets. Yeah you could probably generate pokemon-like looking stuff, but it wouldn't be usable as-is in a game.
Edit: and even today. Generate textures for blocky assets? Sure. But full pokémon models that wouldn't need a ton of rework? Nope.
Edit: and even today. Generate textures for blocky assets? Sure. But full pokémon models that wouldn't need a ton of rework? Nope.