Okay lets see, what about these rumors of Cloud being in PlayStation All-Stars Battle Royale?
There are two interesting german previews based on a closed-door Gamescom 2012 demo. One oft them clearly mentions Cloud as a playable character and the second preview mentions a Final Fantasy Character to be revealed soon.
[...] Dabei stehen euch anstelle von Mario, Link oder Kirby jedoch bekannte Charaktere aus dem Playstation-Universum zur Auswahl. Neben kampferprobten Helden wie Dante, Kratos oder Cloud, werden auch weniger martialische Naturen wie etwa Sackboy mit von der Partie sein. [...]
[...] Instead of Mario, Link or Kirby you have familiar characters from the Playstation universe to choose from. Apart from battle-hardened heroes like Dante, Kratos, or Cloud, less martial natures are like Sackboy to be in on it.[...]
In the comments, the author admits that this was just a slip of the pen. He means Cole from InFamous instead of Cloud. But "Sony said at gamescom 2012, that they will reveal a Final Fantasy character soon".
This fits with a second german preview on the game. Gamesaktuell.de
[...]Helden Ratchet, Spike, Dante und Sackboy zur Verfügung standen. In Kürze soll darüber hinaus noch ein Final Fantasy-Charakter hinzukommen.
[...]heroes Ratchet, Spike, Dante and Sackboy were selectable. In addition there will be a Final Fantasy character added soon.
I know some guys who swears that this second site also wrotes "Cloud" before, but edited the text to this which is quoted above. But there is no proof on that. So we have to wait. Maybe SE will reveal something on August 31. There is a Final Fantasy VII Anniversary stage, too.