I think that the main characters are the children of the two main characters of the first game (most likely there will only be one child, son or daughter accordenly). Also that Team Rocket will try to revive themselfs again in the Unova regoin, but Ghetsis learns of this, and thinks that it would also be a good opportunity to try and revive Team Plasma as well, so he makes a deal with who ever is trying to revive Team Rocket. Since both teams though differ so much on point of veiw one of them trys to take advantage of the other one, and take over both teams. (back to the main character) At some point in the game things get a little out of hand for the main character, and the father/ mother will step in and send out Zekrom (if playing White 2) or Reshiram (if playing Black 2) to handle things.
The reason I think this is because, the main characters of B2 and W2 look similar to the main characters of B and W, to where it would make if the main characters of B/ W where the parents of the main characters in B2/ W2. Also I think Team Plasma and Team Rocket joined forces is because in the trailer for the new games it showes a group of people (supposedly the evil team of the game), they have red hair like the grunts of Team Plasma (like someone pointed out), but they have uniforms similir to that of Team Rocket (what I came to myself). The last part is just a guess of something that might happen to imply that the father/ mother is the main character of the last game.
So what do you think about this? What's your opinion? Do you have any theories yourself?
The CoroCoro scans confirmed that it takes place only 2 years after BW. In the official trailer, the villainous team uniforms are quite similar to Team Rocket's, so this is very possible.
My theory is that the new scientist character is at least morally ambiguous if not a villain, due to his character design, the details about him so far ("mysterious," researching pokemon strength, etc), and the fact that he is not named after a tree or plant. And that Hilbert/Hilda will replace Alder as champion, and change depending which gender you're playing as, or will at least be fightable.
The team rocket thing is possible but I don't think the new protags are the children of the heroes of black and white. It's only been two years since the events of Black and White. I think that during the main story you end up meeting black and white. They're both looking for N because he knows where Ghetis and Prof. Juniper and her father are. You team up with N to beat his father and he shares an important secret from his past. Probably pertaining to his ability to hear pokemons thoughts. I don't know just something like that maybe.
Team Rocket's POSSIBLE but highly unlikely. According to game data evidence, Black/White takes places some years after Kanto/Johto/Sinnoh and Team Rocket's disintegrated into history. Very few members are left at all (one of them tried to revive the team but gave up when he started a family).
My guess is Ghetis. Couldn't get N to achieve world domination so he's taking care of it himself.
"B/W2 plot line is basically you [the player] vicariously going day by day as a stunfisk. The game consists of flapping aimlessly in mud because you serve no higher purpose in the game, getting trampled by trainers and other wild pokemon, and eventually battling that one trainer who forgot to use a repel. If and when you faint, the game fades out into nothing, panning from the body of the defeated stunfisk with the DS system turning off afterwards. The game cartridge ceases to work, and it becomes nothing more than a piece of plastic. "