Complete the indicated task to unlock the corresponding character in Mercenaries mode.

Ada Wong: Complete Ada's Campaign.
Carla Radames: Unlock all other characters and their costumes.
Helena Harper: Complete the Urban Chaos map with a "B" or higher rank.
Piers Nivans: Complete the Steel Beast map with a "B" or higher rank.
Secret BSAA Soldier: Unlock all other characters and their costumes.
Sherry Birkin: Complete the Mining The Depths map with a "B" or higher rank.