Isn't it true for most characters that if you are under the stage with no jumps let, you're dead? The only characters who could survive that are Pit and R.O.B.. Sonics recovery is really good compared to others. His spring dropped can do damage and he can still use aerials afterwards. He does not have many killing moves and is rather lightweight, but also is hard to hit. I'd say he's a pretty balanced out character.
And I can't believe no one has mentioned Pit. Pit is arguably the most overpowered character in the game. He has two moves that reflect projectiles and has an arrow attack that is fast, spammable, and high damaging. His recovery is one of the best too, he can avoid Olimar dreaded Final Smash for crying out loud. He does has a few killing moves, but the are really easy to land. His weight is really his only weakness, but even then he is near medium weight. DAMN YOU PIT!