You can't.
Unfortunately there isn't. if there was they would have to fight Cosmos. Cosmos can't fight so that is why there isn't but if there is I am unaware of it.
Dissidia FF 012 would be better because it's the sequel to Dissidia FF. It includes all the characters Dissidia FF has and more, as well as new costumes, new stages, and the ability to play as the Chaos characters in story mode. Dissidia only let you play as the Cosmos characters in story.
there is no one main character. but i suppose if you wanted to get technical, it would be chaos and cosmos. Signed, Phoenix
no, only the Heroes of Cosmos do. Sephiroth appears in different story modes though, mainly in Cloud's.
As far as I know, it's "Shinryu, the divine dragon". It constantly restarts the battles between Cosmos and Chaos, and it's a reference to a recurring superboss in the series.
Dissidia Final Fantasy. (Unless you are in Japan)
Dissidia is for the PSP.
dissidia is already out...2008-2009
Dissidia Final Fantasy happened in 2008.
Dissidia Final Fantasy was created on 2008-12-18.
Yes in Dissidia 012 their are more characters and 3 stories with which you can embark on one of which are the original 10 from Dissidia. Also more musical scores have been added along with extra collectibles and summons overall 012 is better because it's basically Dissidia with extra stuff.
Cloud is already unlocked in the beginning of the game. If you have a saved data from the original Dissidia, all characters you've unlocked will be unlocked on Dissidia 012.