the latest issue of CoroCoro (a Japanese magazine) revealed a fair amount of info:
- The games are true sequels, taking place two years after the originals.
- The Unova region sports new towns, buildings, locations, and Gym Leaders. New subway lines will take you to new places.
- The Pokedex features 300 Pokemon from every generation. So far, Psyduck is #026, Riolu is #033, Metagross is #254, and Eevee is confirmed but has an unknown Dex number.
- Black Kyurem is confirmed to know Freeze Shock and White Kyurem is confirmed to know Ice Burn.
- There are two new protagonists along with a new rival. The rival has text saying, "Now I'm gonna get angry!" He's the boy with the blue spiky hair. He is your childhood friend.
- Homika is a new Poison-type Gym Leader. She's the girl holding the guitar. She is going to be in an episode of the show in June.
- Shizui is also a new Gym Leader who uses Water Pokemon. He's the tan guy with the goggles.
- There is a new "mysterious guy" named Akuroma who is studying Pokemon strength. Sometimes he'll help you on your journey. He's the guy with the glasses and white coat.
- You begin your journey in Hiougi City. It is on the map in an area that was previously uninhabited in the original games on the left side of Unova (the southwest side). It features an underwater tunnel made of glass (does it take you to the main region?). The city also sports a Pokemon Center, a Trainer School, and shops.
- The magazine points out that there is new construction in the Resort Desert and that there is a new building with red and blue decorations. For the latter it says, "What's it mean?"
credit to http://pokebeach.com/
for this info!