That post with the old R/G vs. R/B artwork of the Bulbasaur Line is exploding with notes, so I though I’d go ahead and make a Charmander one. I originally said that the top row was Red/Blue artwork that is hard to find, but easier than the bottom row, and the bottom row is the ultra rare Yellow Artwork, which was made to match stock anime artwork closer, but a friendly user corrected me.
As it turns out, the bottom artwork came first, for Japan’s Pokemon Red/Green. And the above was made for “Blue Version”, and the international Red/Blue version. So the sstock artwork was actually just flats of Sugimori’s artwork.