Were you the Tucker in that new video thread? Haha. I played vs Legan online over the summer/some games during the Fall. He's really fun to play with =D
Well, some overall things, shield is pretty much the best defense.
For everything except for grabs. Projectile? Shield. Tilt? Shield. Aerial? Shield (lol, sometimes, as long as you can catch them as soon as the aerial finishes).
If you shield something, release right away when the attack finishes so you can punish out of shield.
That said, spindash/spincharge is a horrible direct approach because you're stuck moving no matter what. You can't shield, and you're either forced to jump or spring if something bad comes towards you, so save it for punishments, or just use them to fake someone out.
Same thing with Homing Attack. Pretty much only use it when your opponent can't do anything else, or has limited move choices.
Sonic's specials are good for punishment, and that's pretty much it lol. =p I'll rewatch your vids later and give you more specific advice lol.