Crap, crap, and more crap.
First of all: You call this Sonic old school... Yet, the first thing we see him do is a HOMING ATTACK. This is NOT an old school Sonic move, genius. Secondly... What the hell was up with that Metal Sonic fight? Sonic can't magically teleport, and he can't block the attacks he received simply by crouching. I have to wonder if you've even fucking PLAYED an old school Sonic game, because it's pretty obvious by this lame attempt at flash that you haven't.
Oh, and nice work with the sprites, by the way. No active thruster on Robotnik's machine, and parts of the biplane that shouldn't have been transparent were transparent. Fuck, I'm surprised you actually figured out how to animate the plane's propeller.
This flash fails at life.