Can you trade Pokemon in black 2 to black 2 and what room do you go in?

Several methods are available through the C-Gear which is a key itme you receive early on in the game. Using wireless internet connection it's possible to trade with players in any Pokemon Center on the top floor. For players without internet connection there's also IR connection (infrared). IR is for people to connect with each other that are close by rather than long distanced.

There's also a Dream World and Entralink where you can drop off pokemon for trade.