Silver volta do passado trazendo o Sonic Clássico e o Mephiles, mas Sonic, Tails, Knuckles, Amy, Eggman, Shadow, Rouge, Ômega, Silver, Blaze, Cream, Big, Espio, Vector, Charme, Mighty, Ray, Tikal, Dark Chao, Hero Chao, Chaos, Metal Sonic, Metal Knuckles, Shard, Sally, Scourge, Chip, Bean, Fang, Bark, Jet, Emerl, Zeena, Sticks, Honey e Sonic Clássico lutam e se unem para lutar contra o Mephiles.