There are several characters to unlock in Sonic & All-Stars Racing Transformed on the Wii U and Xbox 360.
Here are the characters you can unlock, and how to unlock them.
AGES – Win Ranger Rush (Sprint) in World Tour Mode: Superstar Showdown to unlock, purchase for 165 stars
Alex Kidd – Unlocked on December 25, 2012
Amigo – Win Studio Scrapes (Versus) in World Tour Mode: Sunshine Coast to unlock, purchase for 8 stars
Danica Patrick – Win Pirate Plunder (Race) in World Tour Mode: Frozen Valley to unlock, purchase for 16 stars
Doctor Eggman – Win all five mirrored Grand Prix cups
Gilius Thunderhead – Win Molten Mayhem (Ring Race) in World Tour Mode: Moonlight Park and purchase for 120 stars
Gum – Win Jet Set Jaunt (Boost Challenge) in World Tour Mode: Moonlight Park and purchase for 105 stars
Joe Musashi – Win Shinobi Showdown (Versus) in World Tour Mode: Twilight Engine and purchase for 85 stars
Mii – Win all five standard Grand Prix cups
NiGHTS – Win Carrier Crisis (Sprint) in World Tour Mode: Scorching Skies to unlock, purchase for 80 stars
Pudding – Win Hatcher Hustle (Sprint) in World Tour Mode: Twilight Engine to unlock, purchase for 50 stars
Reala – Win Nightmare Meander (Ring Race) in World Tour Mode: Superstar Showdown to unlock, purchase for 160 stars
Shadow the Hedgehog – Win Seaside Scrap (Versus) in World Tour Mode: Frozen Valley to unlock, purchase for 35 stars
Vyse – Win Rogue Rings (Ring Race) in World Tour Mode: Scorching Skies to unlock, purchase for 30 stars