The US Keldeo Gamestop Event has started today. You can get it with either Pokemon Black or Pokemon White. The Event runs until October 6 (The day before the release of Pokemon Black 2 and Pokemon White 2).
This Keldeo will unlock the Sacred Sword Event in Pokemon Black and Pokemon White. If your Keldeo has Sacred Sword and is traded to Pokemon Black 2 or Pokemon White 2, it will change forms.
This Keldeo is at Level 15. It knows Aqua Jet, Bubblebeam, Leer, and Double Kick. It will come with a PP Max.
Expect to be asked if you would like to reserve a copy of Pokemon Black 2 or Pokemon White 2.