Sonic (SSBU) - SmashWiki, the Super Smash Bros. wiki

Sonic is a playable character in Super Smash Bros. Ultimate. His return to the series was confirmed on June 12th, 2018. As in Super Smash Bros. Brawl, Sonic is an unlockable character instead of being a starter character. Sonic is classified as Fighter #38. As in Super Smash Bros. 4, Sonic

Falco (SSBU) - SmashWiki, the Super Smash Bros. wiki

Isabelle - Super Mario Wiki, the Mario encyclopedia

Ness, Smashpedia

Diddy Kong (Super Smash Bros. Ultimate), Smashpedia

Sonic (SSB4)/Forward tilt - SmashWiki, the Super Smash Bros. wiki

Sonic (SSBU)/Down aerial - SmashWiki, the Super Smash Bros. wiki

Sonic the Hedgehog, Smashpedia

Super Smash Bros. for Nintendo 3DS and Wii U - Wikipedia

Sonic (SSB4)/Down aerial - SmashWiki, the Super Smash Bros. wiki

Sonic (SSBU)/Up smash - SmashWiki, the Super Smash Bros. wiki

Super Smash Bros. Brawl - Wikipedia

Sonic (Super Smash Bros. Ultimate), Smashpedia

Fox (SSBU) - SmashWiki, the Super Smash Bros. wiki

Knuckles the Echidna - SmashWiki, the Super Smash Bros. wiki