FFI:
Red Mage - of all the starting classes, I feel Red Mage is one of the more iconic classes with the exception of Black Mage. I also feel that Red Mage would be easy to build a fighting style around.

Four Fiends - Let Lich be the main fighter but give him moves from the other three Fiends and you now have all the big antagonist from FFI with a connection to the story. His EX Burst can have all four fiends appear. Hell in reality, just making it Lich would work out as well. The problem with FFI is that all the other villains are sorta "villain of the week" fodder so I can't see them bring in any nostalgia.

Most realistic: Red Mage I think is a realistic entry, I can also see the developers sticking to Lich or ignoring a villain altogether since Chaos does technically count towards FFI.


FFII
Maria - We need more females representing and I feel she's perfect for the villain choice to be against. Maria should be built as an opposite to Firion, specializing in aerial magic combat with limited weapon use on the ground. Her EX-Mode can be her acquiring Lv. 16 magic and her EX-Burst can be Ultima.

Leon (Dark Knight) - I can't really think of a good fighting style for Leon cause you never really see him in action until you acquire him as a fighter. I guess I would make him specialize in using axes and swords and doing close range melee with long range being relegated to magic spells. He'd be perfect storywise, I just can't fathom how he would fight in a way that represents FFII but also doesn't make him a clone character.

Most Realistic: Leon is a shoe in and I feel Maria is also a very likely candidate unless the game chooses to do Josef or Minwu cause fans like them more.

FFIII
Onion Knight (Female) - No one said what sex the Onion Knights really were and even in the games novelization one of them was written to be a girl so this isn't too far fetched. Obviously her Extra costume would be Refia in OK gear . I think she would actually switch job classes a bit unlike the original and I feel her EX-Mode should be FEOK

Xande - Once again, like Leon, his fighting style will have to be made from scratch but I'm pretty sure it will use fog's of darkness as its theme.

Most Realistic: One of the tougher decisions, Xande is a shoe in but the heroes create a bit of a problem, most of the NPC's only have bit parts and I don't see how well they would play out in terms of overall story as opposed to another Onion Knight who can be written from scratch for the plot. Of course there is always the possibility of Doga and Unne...

FFIV
Kain Highwind - Cause Nomura wants him and most of the fans want him.

Zemus - He would complete the circle of manipulation and work as a good foil for everyone storywise. Besides, who doesn't want to see Big Bang in all its glory?

Most Realistic: Kain is obvious cause Nomura wanted him in the first one. Zemus just seems like a no brainer so I feel this pairing is very likely.

FFV
Faris Scherwiz - I have no idea how she would fight considering Bartz unique style but Faris is sorta the other face of FFV considering she appears to have more artwork for her than Bartz. I'd also love to see a really strong female lead as well as the crazy antics her cross-dressing ways would do in the game.

Gilgamesh - The most iconic villain in FFV and the FF series in general, Nomura has already said that if Dissidia 2 was going to be made, he would put him in the game.

Most Realistic: Tough to say, Gilgamesh is a choice for Nomura but it doesn't mean he would be representing FFV specifically and not just be a secret character representing all his appearances. Faris is a popular choice but there is also the possibility they may go the Galuf route as well.

FFVI
Celes Chere - Would be fun to build an opposite to Terra in some ways and I would love to see how they interpret Runic Blade for the game. I also feel she truly is the other half to FFVI in terms of story with the World of Balance being Terra's story and the World of Ruin being Celes'. She's an iconic figure and who wouldn't want her alternate outfit be her opera dress?

Leo Cristophe - A great character to bounce off all the other VI characters and I feel he has far more gameplay options to go with than Ghestahl. It would also be interesting to recreate his blind allegiance to the empire in his story, with Kefka manipulating him.

Most Realistic: Locke Cole was originally chosen by the development team and was only turned down because Nomura felt Terra better represented FFVI (and he loves her character apparently) so he probably a shoe in especially considering his popularity among VI fans. Leo is also not very likely cause I'm sure SE will want to go with big bads like Ghestahl or more amusing choices like Ultros.

FFVII
Aerith Gainsborough - cause she hasn't been a playable character or even a primary character since the original game and she's one of the most iconic and revered characters in the VII mythos. I also feel she would be the most interesting challenge in terms of building a fighting style.

JENOVA - The main McGuffin of VII, JENOVA has a history with all the characters involved. She may not talk but at least her being around will make Sephiroth actually do something in the plot instead of standing around and saying cryptic dialogue that's suppose to make him sound philosophical and cool; but actually makes him look like a silly, pretentious asshole, cause the plot to Dissidia is written by chimps on a type writer...

Most Realistic - Tifa is probably a shoe in, everyone wants a Monk character and she's just as popular as Cloud and Aerith and besides, she would be so easy to develop in a fighting game. Villains are kinda tough cause most of the remaining villains are more of the "armchair" variety with the exceptions of the Turks but they really wouldn't fit story wise. This is actually a tough one.

FFVIII
Rinoa Heartily - Sadly enough, looking at her fighting abilities in the original and how Dissidia works, Rinoa would be easy to develop into the game with her Angelo attacks being normal mode and her Angel Wing Limit as her EX-Mode. She also has a strong connection to all the players involved.

Seifer Almasy - A character originally chosen but removed cause he would feel too similar, I have a feeling the staff will choose their original first pick.

FFIX
Vivi/Steiner - Working like Cecil does and fighting a bit like Onion Knight, these two tag team and switch places in the battle with Steiner focusing on slow but powerful short range attacks and Vivi doing fast long range spell-casting. Ex-Mode would be Trance and their EX-Burst would be Magic Sword: Apocalypse

Beatrix - Mostly cause the other villains wouldn't work as well and she is the villain you fight more than any other. I would love to see her in action with Leo personally. She would also be easy to develop in the game.

Most Realistic: This is all really up in the air and can go a myriad of ways. Beatrix is actually a likely contender but choosing a hero might be an issue. I wanted a tag team group but technically Vivi and Steiner could both work on their own and lord knows if Beatrix is chosen then Steiner is a bit of a giveaway for the heroes. This one is a bit of a mystery...

FFX
Auron - Cause everyone likes him and he would be easy to build for the game. Not to mention his story connections to both Jecht and Tidus would be fun. I also would love to have the game incorporate his "Break" abilities.

Yunalesca - Weak choice but has a better story connection than Seymour. I also feel this would throw a curve ball towards X fans.

Most Realistic: Yuna and Seymour cause they are the other villain/hero from the FFX and were both in consideration in the original.

XI - No idea.

XII
Basch - Cause Gabranth is already in there and none of the other characters would work as his opposite. Besides, Balthier has made so many cameo's he's starting to become the Ivalice equivalent of Cloud and no one likes Vaan.

XIII
Lightning - She's the face of XIII and was originally planned to be in the original. Easy to build a for the game to boot.

Barthandelus - The game's real villain and Nomura has already shown he has no issues re-designing stuff to fit the game so his original form will get a redo for his EX-Mode. Besides, Dissidia already has a Cid and the other villains are pretty weak storywise.

Most Realistic: Nomura said he wanted Sahz cause he came to be his favorite character during development so he's a possibility, as for villains, XIII just might get the XI/XII treatment and only have one representative.

Secret Characters

Zack Fair (Crisis Core) - with all the VII love in the last decade I don't see what Zack couldn't get an appearance representing a spin-off title.

Gunner Yuna (FFX-2) - Yuan to me would not work very well sticking to her FFX incarnation, she has better gameplay options using her X-2 format, so why not skip her for representing FFX and give it to fan favorite Auron and let the Yuna fans have a Yuna character worth using in a fighting game.

Ramza Beoluve (FFTactics) - One of my favorite characters in the FF franchise, I feel he could represent some interesting (and broken) gameplay options and I would love to see him bump against other FF personalities.

Chocobo - He has his own series of games, been a summon for half the series, and he already has experience in a fighting game thanks to Tobal No. 2. Why the hell not, Choco Meteor ftw!

Most Realistic: I think Zack and even the Chocobo are pretty realistic for this category, Gunner Yuna might be the way they do Yuna for her X representation so the only thing unrealistic is making her the secret character over Auron. Ramza, sadly, is probably far fetched. If they did choose a Tactics character it will probably be from the TA series, most likely Luso since everyone seems to hate Marche and SE will assume to choose the most recent entry.