I'm pretty sure that for older games especially, you can link any 2 versions of a given game together. For KOF R-2, for instance, I think the games themselves are exactly the same across all territories, just with a different sticker on the game and label for the box.
Basically, I think that any game that has both Japanese and English in it is a "universal" game.
I have no way of confirming this though. It's just my guess. ^_^