Honestly, I feel only Crash would fit, and even he would feel mostly like a clone of Jak. Spyro as he was in PS1 era would not do well in this type of game, its like asking Nintendo to put Nintendogs as playable characters in Smash. All Spyro would do is charge or spit fire and glide.
I have not played Legend of Spyro, though I have heard its more combat focused, so maybe that Spyro could fit, but that's not the Spyro we grew up playing on PS1. Face it, Spyro just needs to go ahead and die out, not be beaten to a bloody pulp and poked with a stick repeatedly like Activision has done to him.
PSN ID: Troll_Face_Flame (formerly armyflame) X360 gamertag: ArmyFlame9 Sonic Adventure 2 = the last GOOD Sonic game.