If you can't wait for Pokemon Sun and Moon when it arrives on 3DS on November 18, then you will be happy to know that a demo is coming tomorrow that will give you an early taste of the game and a bonus.
The demo will be available on the eShop, and while Nintendo isn't revealing exactly how much will be included in the demo, it did say that Ash-Greninja will appear, and its unevolved form Greninja will be transferrable to the main game when it launches once you complete the demo. Ash-Greninja is from the animated series Pokemon The Series: XYZ.
Nintendo has released a ton of information on the upcoming Pokemon game, from characters to new pokemon, and hopefully the demo will give you the ability to experience much of what has been revealed without spoiling the whole game. At least Greninja is a nice perk even if the demo is a bit short.