>>12494477dem tits
I have to kind of assume that with the main series games, the only kind of "artwork" in a sense would be locals and trainers. Most of the stuff we end up seeing anyways in guides and scans from CoroCoro.
Target had an "Artbook" for a preorder exclusive for BW, but it was mostly just stock Sugimori artwork for the protags, and common Pokemon/starters/legends.