In a certain part of the game, a bulletin board will tell you to go to Route 7, then you will se e Tornadus (Black) or thundurus(White) then you will need to chase it because you only get 1 turn before it runs, you can get its location by the bulletin boards, when you damage it it will keep the damage and status next time you see it .After you get the 8th badge you can catch it.
