(Download for highest quality.)
I agree it's a little annoying not having enough Pokemon X&Y battle backgrounds out there and most of them are all for private use. But I'm here to present you some free to use backgrounds cause sharing is good. If more new BG screens come out before the game I'll make sure to add to this for you guys.
I ripped the backgrounds from the current screenshots and added the battle platforms made by =Snivy101
. Unfortunately this is the highest quality I was able to do due to my limited editing knowledge and that all XY screens aren't high quality. So feel free to mix and match platforms with the backgrounds and edit their colors if you wish; it's up to you. It's the best we're gonna get till XY comes out and someone rips the real stuff. Oh and the reason they're sized 512x384 is because that's the Pokemon Essentials screen size (saved you some re-sizing work). ^^
Free to use but make sure to credit. Oh and link me to whatever you make so I can fave it. Credit - Nintendo / Me / Snivy101