Pokemon Black and White

So I have been playing Pokemon White for a like a month now and I have all the pokemon on my Pokedex but I'm missing one pokemon that can only be found on Pokemon Black (Tornadus). Could anyone help me out? That would be great! Also If you have any Pokemon White Tips or Cheats you would like to let everyone Here know post them now :)

i have him if you want i will trade him to you. my freind code is 1378 3104 8722 btw my name is sarah