Pokemon is it's own weird situation. It's not solely owned by Nintendo, but co-owned and managed with Game Freak and Creatures Inc by The Pokemon Company. It's not just a game but a media empire. They have to coordinate between the game, anime and TCG. It's not quite the same as Zelda or Mario where they have complete control and don't have to worry about messing with dozens of other product launches if the game needs a delay.

I wouldn't agree that their other franchises are stale right now either. Certainly not compared to Ubi's, Microsoft's, etc.