There are all kinds of different reasons for choosing to write one story over another. For instance, I'm telling you about a Pokémon-centric GameStop promotion solely to irritate Joystiq co-worker and co-brother Griffin McElroy with my ignorance. It's a pretty big sacrifice for a major gaming website with millions of readers, but Griffin loves Pokémon more than you love most members of your immediate family, so it's absolutely worth it.
So, apparently, if you take Pokémon Platinum, Pokémon Diamond or Pokémon Pearl (are there really that many?) into GameStop between January 30 and February 14, you can get a Pikachu-colored Pichu. That Pichu will also give you access to the mythical, spiky-eared Pichu in Pokémon Heart Gold and Pokémon Soul Silver (There are more of them? And they're called that?!). So make sure to say "Hi" to Griffin and his girlfriend there.
Oh, and by the way: That thing to the right is a Pichu. I don't know how to break it to you, Griffin, but he is Pikachu-colored and has spiky ears.