Even if they really used those models, there's still modeling everything aside from that, which is effort considering GF only did tile-based graphics before. There's a lot of breaking new ground and re-evaluating old ground that went into XY that probably took a lot of their time and made them rush against the engine features and Pokedex.But they released the Pokedex app with 600+ 3D modeled Pokemon, so all that work is already done.