There are several unlockable costumes in Resident Evil: The Darkside Chronicles for the Wii.
Here are the costumes you can unlock, and how to unlock them:
Chris’ Caucasus Costume – Complete Operation Javier: Chapter 5 on Normal
Chris’ Mafia Costume – Get an S rank on Game Of Oblivion: Chapter 7 (final) on Normal
Claire’s Biker Costume – Get an S rank on Memories Of A Lost City: Chapters 1 through 8 on Normal
Claire’s Western Costume – Get an S rank on Game Of Oblivion: Chapters 1 through 7 on Normal
Krauser’s Detective Costume – Get an S rank on Operation Javier: Chapters 1 through 5 on Normal
Krauser’s Mercenary Costume – Complete Operation Javier: Chapter 5 on Normal
Leon’s Agent Costume – Complete Operation Javier Chapter 7 on Hard
Leon’s Biker Costume – Get an S rank on Memories Of A Lost City: Chapters 1 through 8 on Normal
Leon’s Detective Costume – Get an S rank on Operation Javier: Chapters 1 through 5 on Normal
Leon’s R.P.D. Costume – Complete Operation Javier: Chapter 7 on Hard
Steve’s Western Costume – Get an S rank on Game Of Oblivion: Chapters 1 through 7 on Normal