To get the below secret characters you must beat the Aracde Mode with each of the original characters. One bonus character is revealed each time you beat Arcade Mode with a different standard character. The order you get the secret fighters is as follows:
1. Kuma
2. Julia Chang
3. Gun Jack
4. Mokujin
5. Anna Williams
6. Bryan Fury
7. Heihachi
8. Ogre
9. The Real Ogre