Cruising Bogleech’s pokedex reviews, I learned about the swap of Butterfree’s and Venomoth’s designs (likely by mistake) in Gen I. While I doubt the change to be highly significant, I do wonder how this mistake influenced the franchise. After all, Butterfree is the most iconic Bug pokemon (outside possibly Scyther), one of the beloved first catch of many players, the model for many latter pokemon, and played a big part in the original anime. How much do you think this change affected things?
It’s sort of obligatory for me to point out first that we don’t know this is true; to my knowledge no-one at Game Freak has ever confirmed or denied it, and they probably never will. There’s enough evidence for it that it seems plausible to me, but there are some things we probably can’t ever know for sure – heck, maybe there was a switch, and they did it on purpose, precisely because they preferred the idea of the starting Bug-type ending up as a cute butterfly. But anyway. Assuming it’s true, well… I’m not sure changing two Pokémon affects the fate of the franchise all that much. Venomoth makes just as much sense as a precursor to Beautifly, Dustox, Vivillon, etc as Butterfree does, and Caterpie is going to be your beloved first catch no matter what it evolves into (maybe I’m just saying that because I like Venomoth anyway, but presumably I’m not the only one). Butterfree’s never really been a flagship publicity Pokémon, either. The exception is the anime, where Butterfree is important as Ash’s beloved first catch. I think the biggest difference is that I don’t know if I can imagine the episode Bye Bye Butterfree, when Ash’s Butterfree falls in love and leaves him to go and start a family, being written the same way with a Venomoth, because the emotional moments between Butterfree and Ash might not resonate with a Pokémon so… un-cute. But it’s not as though Venomoth is so thoroughly hideous or alien that it’s impossible to empathise with.