How do you get the Raiden outfit in Assassin's Creed: Brotherhood?

Answer 1

Raiden's CostumeComplete all of the tasks in the Animus 2.0 training mode with at least a Bronze Medal.

Got this from gamefaqs.com

Answer 2

After playing the story mode for a while you will unlock virtual training, a set of game modes designed to help you become a master assassin. Play each one and score at least a bronze to unlock the Raiden outfit. If you then go to the same place where you would change capes, you will see an outfits option. There you can now change to raiden otufit XD he has no special abilities that Ezio doesn't have, but he does look pretty awesome :P

The outfit is in the game because Konami featured Altair's outfit in Metal Gear Solid :D

Answer 3

Finish all the stuff in the Animus 2.0 with a medal.

Answer 4

You can obtain the Raiden outfit in Assasin's Creed: Brotherhood from earning a bronze medal in each task in the Virtual Training section of the Animus 2.0. Virtual Training is unlocked once you progress far enough into the story.