Credit goes to THExZAK for the 360 solution for the original costume unlocks
There are a total of ten costumes in the campaign. Six of those are unlocks. The stipulations for unlocking the alternative costumes are as follows:
Chris
- Safari (beat the game once)
- S.T.A.R.S. (find 25 of the BSAA emblems)
- Warrior (unlocked at the start)
- Heavy Metal (beat the game once)
Sheva
- Clubbin' (beat the game once)
- Tribal (find 30 of the BSAA emblems)
- Business (unlocked at the start)
- Fairy Tale (beat the game once)