SaniOKh

Too old for this stuff

Age 35
Male
Ukraine
Seen 4 Weeks Ago
Posted October 22nd, 2021
591 posts
16.9 Years
The title of the thread is absolutely correct: it is because you don't have the National Pokédex yet, and Crobat isn't part of Kanto Regional Pokédex.

See, for a brief period of time (covering Gen 1 remakes and Emerald) Pokémon games didn't allow you to have any Pokémon outside of the Regional Pokédex if you didn't have the National Pokédex. Your Pokémon is supposed to evolve into it? Tough luck, 'cause it won't. You want to trade a Pokémon from another game? Unless it is in the Regional Pokédex, the game will outright refuse to accept it.

Again, this is only in FireRed, LeafGreen and Emerald. Ruby, Sapphire as well as later games allow you to have all the Pokémon you want.