Approved by TM2-Megatron.
Inspired partly by Bulbapedia's trivia, here you can post little-known facts and interesting obscurities about the Pokemon games. For example:
*A female Azurill can evolve into a male Marill
*Shellos was originally meant to be in Ruby and Sapphire
*Latias and Blaziken were once one Pokemon
*There is no Route 23 in HeartGold and SoulSilver
*Moltres has been obtainable in six different regions; Kanto, Johto, Sinnoh, Orre, Oblivia, and the Sevii Islands
*Pokemon Gold and Silver were once known as Pokemon 2
*NidoranF can breed, while Nidorina and Nidoqueen can't
*Charizard and Rhyhorn share the same cry
*There existed 31 different cries in Generation 1. The rest were variations of the originals.
*Mew was programmed into Red and Green without the knowledge of Nintendo
*Leaf appeared in artwork of Generation 1, only to make her first appearance, after being completely redesigned, in Generation 3
*Poliwhirl is Satoshi Tajiri's favorite Pokemon, and thus inspired to be Red's - from Pokemon Special - first Pokemon
I'm looking forward to reading what other cool facts you guys know.