Obviously I know about the three original starters, but when I was on Bulbapedia trying to look at who made the cut into X and Y, it said that everyone else I looked up wasn't available in the wild, just through trading. Even Pikachu and Mewtwo, though, who have been featured fairly prominently in the marketing. So, I figure that's just not updated yet.
So, who else is in there? Is there some list someone can point me to?