Big Daddy-Big Sister
(i dont know how this would work, but it would rock)
Sly: Pirate costume (Sly 3) or Venice Guard costume, Tux from Sly 2.
Jak: Jak 2 costume or TLF costume or Prision costume
Ratchet: Dan or Alister, or Gladiator costume.
Nate: Doughnut Nate or Harry Flynn, or Tux from Uncharted 3.
Good Cole: Zeke or a Ice Guard.
Evil Cole: Full Vampire Cole or Vampire Guard.
PaRappa:Noodle gang costume from PaRappa 2.
Spike:Buzz (Or Jake in the USA), or Jimmy
Sackboy: Yellow Head
Raiden: Gray Fox
Big Daddy: Delta
Ratchet: Deadlocked Armor
Kat: Maid (Assuming that's not one of her alts in the DLC)
Dante: Classic Dante DmC version
Toro: Beast Cat (Justice = Snail suit, Ninja = Fish suit, Oni = Another animal he dresses up as)
I don't get all the love for the Deadlocked armor. For them to put Ratchet's Deadlocked costume in Superbot would have to redo all of Ratchet's animations since they are linked to the character build. They would have to remake all of Ratchet's attacks coincide to a much taller modeled character like Dante. Just adding his 6 foot tall Deadlocked costume to his existing 4 foot tall character animations would end up a freakish nightmare like this one from Brawl
This pic was from when a hacker switched Snake (or someone's animation) to a Pikachu skin. The result might not be quite that bad, but it gives you an idea what Superbot would have to do to add Ratchet Deadlocked.
and fat princess as muffintop or a ninja (if you buy the dlc and hit the directional buttons on the start screen she changes into one)