FACT: Uhh Sonic has like 2 attacks total dude.
Actually Sonic has probably had more attacks than any other platform game hero (except maybe Kirby).
Off the top of my head Sonic can...
-Spin when he jumps which is actually an attack (all his games)
-Spin Dash (almost all his games)
-Homing Attack (All the 3D Sonic games & Sonic Advance 2)
-Create blueish wind that hurts enemies in some way (From SA2 multiplayer, I forgot what it was called)
-Use Chaos Control to teleport (SA2)
-Use Chaos Control to stop time (SA2)
-Use Chaos Control to create spears of energy (SA2, actually Shadow does this but I assume he can too)
-Do a Megaman-ish slide attack (SA2 & Sonic Advance 1-3)
-Slam himself into the ground to bounce higher (SA2)
-Use Light Speed Attack to attack a group of enemies at an incredible speed (SA1)
-Use Light Speed Dash to follow a ring trail or dash to a single ring (it was used as an attack in Sonic Battle)
-Make a wave of blue energy during a jump (Sonic 3, Knuckles & Sonic Advance 1-3)
-Use the powers of various elemental shields (I.E. fire = flame dash) (Sonic 3 and Knuckles)
-Shoot a wave of blue energy (Sonic Battle)
-Throw various punches & kicks (Sonic Battle)
-Not to mention Sonic is super strong, probably even stronger than Mario.
And his Finale Smash is a no-brainer, he could transform into Super Sonic.