Sonic (SSBU)/Neutral aerial
Curls up into a ball and spins while slightly undulating up and down. In addition to being a reliable follow-up from Spin Dash, Spin Charge, and Spring Jump-assisted combos, its launching angle, fast startup (frame 6) and low landing lag (10 frames) allow its clean and late hitboxes to serve as useful combo starters at low to medium percentages when SHFF'd, allowing it to be followed up by any aerial. At high percents, landing immediately with the late hit can combo into a back aerial, which can lead to a KO near the ledge.
It resembles the Air Spin from Sonic the Fighters and the Insta-Shield, an attack that debuted in Sonic the Hedgehog 3.