I don't recommend playing Alpha/Sapphire yet. It's playable at the beginning, but soon you will get a lot of freezes.
If you find a "Starter save" for pokemon X/Y, you will be able to play it. The thing is that it's not optimized yet. Sound doesn't work and crashes are common.
As lg said, Sun and Moon are the best option for Citra right now. I've played for more than 50 hours, finished the story and got no freezes at any point. It's not full speed all the time, but it's a solid experience.