|YAY, she's not a Gunner!|
EDIT: So it turns out the rest of the info is barely anything. Yuna can summon up to 2 Aeons at a time and her EX Burst is Sending, which summons all of her Aeons to obliterate the opponent. Also, a while back, Tifa's bonus costume for the European version got revealed. It's her Amano outfit without the white/silver/platinum blonde hair. Goddammit, that's lazy! Plus, it turns out the bonuses you get for transferring your regular Dissidia file are your characters keep their levels and you get a special accessory, and there can be 5 on 5 fights! Plus, you can create you own quests like the story mode! Please March, come soon and grace me with this great game and Pokemon Black...
*The only reason I like Summoner Yuna better than Gunner Yuna is completely because of her hairstyle and choice of clothes. Yup, that's it. Also, her voice sucked in FFX, but in Kingdom Hearts II(I haven't played X-2), she sounds like a totally different person! They need to keep it that way!