North American Pokemon trainers are getting a free gift over the next week. If you connect your game to the Nintendo Network, you will find a Shiny Yveltal as a Mystery Gift free of charge. In order to access the Shiny Yveltal, go to Mystery Gift > Receive Gift > Get Via Internet. The offer will end next week on May 26th, so you don't have much time.
Yveltal is the mascot for Pokemon Y and a powerful addition to any Trainer's lineup. It also doesn't hurt that it's a super rare Shiny version that will make people around the world throw literally anything your way on the Global Trade Network, if for some reason you don't want it.