If Xbox and Sony can have one Character in Smash..

[Landale_Star]

Sony- Ratchet and Clank
Microsoft- Banjo-Kazooie

Runners up
Sony- Kratos, Sir Daniel Fortesque, Spike (Ape Escape), Virginia Maxwell (wild Arms 3)
Microsoft- Master Chief, a Battle Toad, Sabrewulf, Juno/Vela (Jet Force Gemini)

Could probably come up with a few more for both of them.