itch.io

There's a Nidoran in Chroma City playing with a little boy.

It keeps switching from Nidoran (Female) to Nidoran (Male)

Is it only me who has this bug?

I can't find one either. I gave up and just caught other Pokemon instead. And there is a way to get Squirtle as well as Bulbasaur if you choose Charmander.

SPOILERS

Once Professor Oak has left his lab, you can steal Bulbasaur's Pokeball from the table it was left on. As for Squirtle, you need to defeat your final opponent in the Final Dungeon's third floor.

Your guess is as good as mine. If I had to guess, I'd say you have to complete everything the game has to offer, but I'm unsure.