Some very interesting material that Sony can use.
Kratos will be good, along with Nathan, Sly and Sweet Tooth. Surprised that Parappa and Fat Princess get a look to be honest, those games are a little niche in their appeal and haven't seen any action for a while.
Unless this game will also serve as an advertisement for sequels I really don't understand wasting the effort designing characters that won't sway many people.
My ideas;
Sackboy could be heavily reliant upon the scenery, building temporary obstructions or pathways to confuzzle his opponents. Most of his damage coming indirectly (like building a trampoline to fire back enemy projectiles) he would require an advanced player to properly utilise.
Cole MacGrath (of whom will be appearing in Street Fighter X Tekken as well); has a lot of potential - as well having the option of being two characters, with his Evil and Pure Karma incarnations.
Jak has a lot of versatility, with multiple firearms at his disposal, Daxter for annoyance and distraction attacks and of course Dark Jak when things gets serious. If the game was to entertain the prospect of "Home Stage Advantage" perhaps Dark Jak could be activated by slipping into some Dark Eco?
Ratchet would be similar in execution to Jak I imagine, but with a lot more focus on the gadgetry. Perhaps he would be permitted to have an equipment set up so no two Ratchets would be the same. Jet Clank or Hydro Clank. Disco Ball or Morph-o-Ray.
THose are the main players I can think of, others spring to mind like Nariko - but they seem to small time to really be an attractive prospect.