Spin jump

The spin jump is the primary offensive maneuver of Sonic the Hedgehog and friends in the Sonic video game universe. Unlike hop-n-bopper heroes such as Mario or Diddy Kong, who must make contact with their feet in order to defeat a badnik, the spin jump enables the character performing it to roll up into a ball, causing most badniks that come into contact with any portion of him/her to be defeated. The theory behind this behavior is that when Sonic performs the move he rolls up into a ball, causing his spines to be exposed. These spines combined with the intertia and momentum of the jump is what causes the enemies to take damage. Enemies that utilize spikes, flame, and extreme cold counteract the spin jump and cause damage to the character performing it.

The move first appeared in the original Sonic the Hedgehog game. When Tails was introduced in Sonic the Hedgehog 2 he was also able to pull off the move, although why it is effective in damaging badniks is unexplained as Tails has no spines to cause damage with, but it is theriorized that he spins quite fast, and lets him deal damage. When Knuckles was introduced as a playable character in Sonic and Knuckles he was also able to perform the spin jump with his spines, setting the precedent that the move is the standard weapon of playable characters in the Sonic universe. Cream the Rabbit, Shadow the Hedgehog and Rouge the Bat can also perform the spin jump. Major characters who are unable to perform the spin jump include Amy Rose before Sonic Advance 2 (who instead is armed with a large hammer) and Dr. Robotnik (who fights from his personal battle mech).