Does the Keldeo wi-fi event work with either game (Black/White or B2/W2) or does it have to be black/white (and then traded to 2).
The event is only for BW2.
It's for Black 2 and White 2.
Black and white 2. Source - I got one for myself.
It works for both games. You can trade them back and forth as much as you like but you will need 2 DS's or a friend must help you.
Only on B2/W2. You'll have to trade one to B/W.