>>27407711according to Sugi's artbook, gen 1 pokemon where drawn directly to sprites by the dev team (and is hard to give credit to who did who, although he worked on some of them), later when a strategy guide asked for artwork for all of them sugi had to draw them all in a singular style.
There was always more than one person making pokemon designs and this is kinda know principally because Satoshi Tagiri designed rhydon, slowbro, gengar and more.
