Joystiq
Joystiq News
Niantic promised on December 12th, and it's delivering... with an interesting twist. It's not only adding "several" new critters from the Pokémon Gold and Silver games (such as Pichu and Togepi), but also releasing a limited edition holiday Pikachu. The Santa cap-wearing creature is available "all over the world," but only until December 29th at 1PM Eastern. If you don't find one by then, you're out of luck.
Source:
Console Bang News!