Coming from an interview with NowGamer...
"Well first of all, we talk with the Pokemon company. What’s the hot Pokemon? What Pokemon are in the movies right now? And really do a lot of research on that front.
For example, X and Y are coming out – of course, we haven’t done any market research because they’re not out yet, but we look at the animated series or movies and anything like that and again, find out which ones are going to be central to any of conversations in Pokemon going forward.
But it’s not just that – going back to just what we talked about, what’s unique about them? Where do they fit in with the rest of everything else? What do they have? It’s a combination of those things."