With the wrap up of the developer roundtable for Pokemon XY comes the announcement of many fun new things.
Of note are things like:
Horde Battles: Fight many Pokemon at once, but if your Pokemon doesn't have any moves that can attack multiple targets, you may be in for a challenge!
Sky Battles: Fights where only Pokemon that can fly are eligible to participate.
and 3 more Pokemon:
Talonflame, the evolved form of Fletchling:
Clauncher: a pistol shrimp
and Skrelp: A leafy sea dragon.
Horde battles sound pretty exciting. They also mentioned they are working on the way they will handle backwards compatibility.
Here's a brief video overview of the Nintendo Developer Roundtable, where they talked about it.