Lightning fight (the player sucks lol)And some scans from Famitsu, I think:

Take a look at the screens a little closely, and you'll see 4 characters on the screen. Apparently it's an assist system, like Marvel vs Capcom, where you can 'tag' another character and have them come in to deal some additional damage and maybe keep a combo going. You see it in the video above actually around 35 secs in and see Warrior of Light helping Terra. I don't know how true this next piece of info is, but apparently, the full cast from the first Dissidia returns and there's also some support for anyone with a save file of the first Dissidia, though it's not been mentioned what it is.
Supposedly, there's also a trailer already shown at TGS confirming another character. Can you guess? I'll give you a hint, I suggested her inclusion in the previous page

I'll definately keep an eye out for this trailer.