Venonat's color, hands, eyes, mouth and antennaes are somehow similar to Butterfree's unlike Caterpie or Metapod. On the other hand, Metapod's eyes, head shape and body looks similar with Venomoth's. There might be some designs that have been interchanged by Game Freak. Or is it just me whos not good enough with Pokemon evolution? LOL
Nice observation, but gamefreak isn't going to mess up evolution like that and then make it permanent. TBH the butterfree line make sense because that's how the evolution is supposed to go. Venonath is supposed to turn into a moth, and I don't know about moth's but I'm sure gamefreak wasn't stupid about that either