>>713487847They will propel you in a direction, so N-shoulder button does a reverse, where the character throws themselves backwards.
F-shoulder goes forward-
D-shoulder does a ground-pound (only Sonic and Knuckles can use these to break ground objects)
And Up-shoulder, which hurls you up.
Sonic also can-
Homing attack/insta shield
Ground pound (Jump, hold+down, jump button)
and Air dash by hitting a directional twice in the air (you can chain these, and break the bosses with it).