Gamestop is offering the mythical colt Pokemon Keldeo now until October 6th.

This is the only way to obtain this Pokemon in the game.  All you need is a DS, a copy of Black/White, and any Gamestop.  After you get to the GameStop, you just need to start up your game and go into the “mystery gift” section.  Next, select “receive gift” and then “get via wireless”.  PRESTO!  You are now the proud owner of a Level 15 Keldeo.  Keldeo is a Water- and Fighting-type Pokémon and come with these moves: Aqua Jet, Leer, Double Kick, and BubbleBeam.  It also has the ability Justified, which it shares with Terrakion, Cobalion, and Virizion.

That isn’t all you can do either; you can transfer it into your Pokémon Black Version 2 or Pokémon White Version 2 (which are scheduled to be released in North America on October 7, 2012, Australia on October 11, 2012 and in Europe on October 12, 2012.)  This will let you complete an in-game event that will teach Keldeo its signature Secret Sword move and reveal it’s Resolute Form!

[News; Keldeo]