Once you download the Versus DLC, you may buy the following characters from the Bonus Features menu using your accumulated exchange points.

Character	How to unlock
Chris (S.T.A.R.S.)	13,000 exchange points
Chris (Safari)	8,000 exchange points
Jill (Battlesuit)	7,000 exchange points
Jill (BSAA)	5,000 exchange points
Sheva (Clubbin')	6,000 exchange points
Sheva (Tribal)	15,000 exchange points
Wesker (Midnight)	30,000 exchange points
Wesker (S.T.A.R.S.)	50,000 exchange points