Dissidia 3
Since it's pretty much confirmed that Gilgamesh and Prishe are the last new characters to be added in Duodecim (judging by the fact that sans FFI, every game that has yet to receive a new character gets a new stage instead, those being FFII, III, VI, and IX), I think it's safe to say that we can start theorizing on who would be the best representative characters for
Dissidia 3.
FFI: Princess Sarah,
Black Mage, or
Matoya.
FFIII: Xande for sure. He is the primary antagonist throughout the bulk of the game.
FFVI: Locke. Like Vaan's relationship with Ashe, Locke is a bystanding protagonist, watching the main story unfold and revolve around Terra and Kefka. As a thief-adventurer, he brings a new gameplay mechanic to the series.
FFIX: After giving this game a lot of thought, I believe that
Zorn and Thorn are the perfect representatives. Not only do they introduce the new playstyle as a tag-team duo built into one 'character', but they also represent the overlying theme of FFIX with the paired relationship between Gaia and Terra. As recurring minor antagonists, they are both memorable and important. On top of that, they already have an EX Mode:
Meltigemini and an EX Burst: Viral Smoke.
FFXI: Seeing as how XI currently has two Warriors of Cosmos, it definitely needs a Warrior of Chaos. So, do we choose
Shadow Lord,
Eald'narche,
Promathia,
Lady Lilith, or who else? Seeing as how Promathia is fought by Prishe and is quite different from every other Dissidia character, I think he would be the best bet. Also seeing as how Promathia is the antithesis to Altana, the goddess and creator of Vana'diel, how can that not be the best pick?
FFXII: Balthier.
FFXIII: Without a doubt,
Galenth Dysley. He was a hell of an antagonist and if it's not obvious enough, his EX Mode would be his true form
Barthandelus with Thanatosian Laughter as his EX Burst.
A second rep from the FFXIII universe would most likely be the new "purple guy" from FFXIII-2, or
Noctis from FFversusXIII.