The starting roster is

Sonic, Tails, Knuckles, Cream The Rabbit, Amy, Charmy, Vector, Espio, Shadow, Rouge, Silver, Blaze, Dr. Robotnik, Metal Sonic, Big The Cat, and Zavok, each having their own skins to choose from. If you don’t like that, the playable avatars from Sonic Forces return.

I don’t know why Omega is left out when pretty much every other character to serve on a three person team is here, or why Zavok is the only member of the Deadly Six that Sega like to remember exists.