Only the previous generation Pokémon have Entralink OW sprites.
Anyway, you're overlooking a much bigger problem.
Pokémon sprites in BW are not frame-by-frame animation. They're segmented pieces drawn on a 256 x 128 map, stitched together by the engine in-game and animated using part swapping, auto transformation/rotation/scaling and moving each segment individually.
So, good luck hacking all that.