I saw the new trailer of KH2 and I came up with this theory that Yuna, Rikku and Pain might be summons. It makes sense because they wouldn't have a story about her because Tidus is a kid in the game and it would be wierd to have two Riku's. Plus in the new 15 seconds trailer I saw them as kids, that could be when Sora first unleash them. I could be wrong because Heddy Burres is playing as Yuna.