This isn't trying to copy Skyblade's topic, I thought of posting it after reading Auron Lu's short story Venus Rising. I imagine you can guess who became the Final Aeon in the story, and its a very good description.
So my question is: what characteristics would Yuna's Final Aeon have? You can include powers, stats, appearance etc. In terms of who would qualify as a Final Aeon, I would say the only restriction is that he/she must have a close emotional bond with Yuna. So if you think that Seymour (or even Keepa!) was close enough to her, then go ahead.
So here's my attempt: Final Aeon Lulu: High Evasion, Magic and Magic Resistance. Alternately casts Death and Flare. Overdrive: Ultima. Appearance: An ice queen of goddess-like beauty (like Lulu only bigger!) Special power: complete resistance to elemental magic (like a Dark Aeon)