I'm just gonna go the safe route and hope that we get Cloud's release, a Wolf announcement, and 2 newcomers, one from an already represented series, and one from an unrepresented series.
Oh, also 4 stages (Midgar, one for each newcomer, and a throwback stage, hopefully from Melee seeing as that game hasn't had any DLC stages here).
And obvsly some Mii costumes. Chocobo, Tifa Brawler, Sephiroth Swordfighter, Barrett Gunner, Black Mage/Vivi, and a couple others.