>>46737936It was coded later, i believe. Kind of a Mew situation, GF saw they had space for one more mon and added it, except this time it was a random filler shitmon instead of a ultra powerful legendary. Maybe that's why Gardevoir is also so late in the coding despite being an early game mon, they wanted to make either something that would make sense for Wally to catch without Zigzagoon taking damage first or an early game shitmon that wasn't the usual bird/mammal/bug, but only planned it after coding most of the Pokedex in. That's what makes sense for me at least, i don't know if there's an official answer.
