The female Player Character is known as White. It has also been used in screenshots of her as another player; Black visits her World.
Don George and Swanna have both been called "Carl" for their slight resemblance to the Aqua Teen Hunger Force character while the new early bug, Sewaddle, is going by Countapillar, Bugleaf, Smugbug, Fraterpie, Collarpillar and Vampillar.
Sarcophaghost for Cofagrigus. However, that exceeds the games' character limit, so coming up with shorter names is a bit of a pastime.
Koffin. And it's one letter removed from "Koffing", too.
Genosect + 4chan + Mondegreens = DENNIS. It hasn't been stopped by the discovery that the song in question isn't Genosect's theme as far as we know.
"Pokémon Gray/Grey" for the inevitable third game.
Which is likely true, based on the fact that the most likely third member of Reshiram and Zekrom's trio is grey with pale blue accents, and the name was trademarked at the same time as the names of these games. It's either "Pokémon Gray," or "Pokémon Transparent."
Urban Legend of Zelda: Mostly averted, as despite pretty much half the internet going crazy over this game, any rumours without at least some proof are quashed almost immediately. Though, there have been several instances of faked screenshots and CoroCoro pages being hidden among legitimate releases from CoroCoro and Pokémon Sunday by some of the people who leak them. The problem is getting worse every single time a new batch of info is released. Justified in that there are legions of fan websites ready to debunk these rumors as well as long-time fans that are probably Genre Savvy enough to know better. This hasn't stopped the occasional hastily added entries to this page, however.
What Could Have Been: Originally, Frillish and Jellicent were supposed to be just a pure Water-type species, but for the sake of type distribution, they were changed to a Water/Ghost type (a type that hasn't been seen prior to Generation V). This resulted in their creator (a new artist working at Game Freak) being disappointed with the scary aspects (such as causing ships that cross its habitat to be sunken and all of the passengers on board to end up missing) being added to what was supposed to just be some normal jellyfish based on princes and princesses.
Stunfisk was also supposed to be Electric/Water type. This was changed for the sake of type distribution.
Deino, Zweilous and Hydreigon were originally intended to be cybernetic dragons incorporating aspects of tanks within their bodies. The track-like markings on their bellies seem to be a remnant of this.