How do you unlock Shadow in Sonic Free Riders?

You can't unlock Shadow in Sonic Free Riders. Shadow is not a playable character in this game. The playable characters are:

* Sonic

* Tails

* Knuckles

* Amy

* Cream

* Big

* Silver

You can unlock special costumes for these characters by completing certain tasks in the game, such as:

* Completing races

* Achieving certain scores

* Unlocking hidden items

However, Shadow is not one of the unlockable characters in Sonic Free Riders.