What are the hidden moves in Sonic Advanced 2?

Answer 1

Sonic and Amy's Secret Move

• There is a secret move in "Sonic Advance 2" you can use to make either Sonic or Amy jump higher and farther than normal. Simply jump off from the end of a rail after grinding it and your character will do a mid-air somersault, allowing them even more height and distance on their dismount.

Knuckles' Secret Move

• Knuckles has a very effective secret move that you can use to make short work of any boss with the exception of the final one. Hold "A" while gliding until Knuckles starts gliding on his belly, then hold "Down." Releasing "A" once makes Knuckles duck down, and pressing it again completes the maneuver.

Answer 2

There is one move for Sonic:

Air dash - Tap the control pad while in the air after a jump for a burst of speed in the air.