Just kick the game's ass in every way possible, and you'll wind up with everything. It isn't Guilty Gear, they're not going to unlock things over time. Pick a character, practice practice practice, and then own on the A.I. until your thumbs hurt. Then, those secret characters will be a lot more valuable, too.
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"Word I was in the house alone,
Somehow must have gotten abroad:
Word I was in my life alone.
Word I had no one left but God."