Originally Posted by Fat gabe lavail
I'm guessing that the rotation is going to be CoL-On. The change in ultra rares is a pretty large indication. Pokémon likes to rotate 4 sets at a time, remember the rotation to MD-on? The reprinted a bunch of cards in Call of Legends that Pokémon feels are healthy for the format, Dual Ball, Cleffa, Oak's, Ninetails etc... Black and White on makes less sense in my opinion because then we wouldn't have a solid way to search out basics. All of that would have to be done with Ultra Ball and Level Ball. This would mean the format would be a lot more luck based, it'd depend on what you draw.
We'd still have a way --- the use of attacks like those on Elgyem, Lapras, and coming out soon Emolga and Shaymin --- but it wouldn't be as powerful. Some decks already benefit from having Pokemon search attacks on their basics, like promo Litwick in Chandelure or Foongus in a status condition deck; that role could potentially become more important, or decks could just shift to be less reliant on full benches. We could also go back to using Pokemon Communication I guess. :)
We also don't know quite what we'll get in the September set; we can look at the Japanese Dragon sets and make an educated guess, but Pokemon could conceivably juggle things around a bit to make a BW-on format more viable if they wanted to. I don't think there's much we can do except wait and see.