I'm assuming this game would be with mostly 1st/2nd party characters, with a few 3rd party cameos. In which case, my characters would be:
Jak
Spyro
Ratchet
Nariko
Kratos
Sly Cooper
Dart
Tiny Tiger
Genji
A plush-man from LBP lol
Sweet Tooth
Jersey Devil
Kannuki from Bushido blade
Rudy Roughnight
3rd party cameos:
Sora
Cloud or Sephiroth (can't be greedy)
Snake
Jin Kazama
Not TOTALLY complete...but a good start