Damn, if this is true, that's incredible! I'm sure that PokeFans all over the world have been waiting for something like this!
I know I shouldn't get my hopes up, but I don't care haha :]
Although I do have my doubts. BW1 took place how many years after GS/DP? 10? Wattson & Blaine must be close to, if not already retired. Also, Giovanni? What is he doing here? Could Team Rocket be coming back AGAIN?
However if I recall correctly, Cynthia did say something in BW1 about Champions from all regions gathering in Unova.
Found it: "Once every few years, the Champions of each region gather and compete to see who is the strongest! An interesting idea, don't you agree?"
So that COULD be a sign that the rumor is true!
I will be so dissapointed if this rumor turns out to be false, but it does seem way too good to be true. :[
Cheren as a Gym Leader? I wouldn't doubt it. Black & White 2 is basically the Gold & Silver to Black & White, and your rival in Red & Blue does turn out to be a Gym Leader in GS. Maybe Cheren is the final Gym Leader you have to face?
Location: Preparing for trouble and making it double.
As much as I adore this, I am very skeptical. The idea of having over 50 trainers with high level Pokémon to battle sounds too good to be true. This certainly would get people who may have not bought the game to now buy it though.
Perhaps only a select few of the gym leaders would appear...40 gym leaders from the old generations and BW seems like too much...Personally I would like to see Brock, Misty, Geo, and Blue from Kanto; Falkner, Clair from Johto, All of Hoenn Roxanne, Braly, and Wallance and Juan from Hoenn; Roark, Volkner from Sinnoh; and all of Unova (because we are still in Unova).
Well, maybe each gym leader is accessible by a wifi event. Like, "the misty wifi event - to enable battles with misty in the world tournament, download this ticket" or something, like every month which gives people something to look forward to rather than all at once? :x