There are three different-looking dolls which are based on Dr. Eggman's greatest enemies out there. These three variants are Sonic Doll, Tails Doll (not to be confused with particular one from Sonic R) and Knuckles Doll. These dolls bear little resemblance to the actual characters, and are poorly made.
In Sonic Adventure and Sonic Adventure DX: Director's Cut, the dolls are used by E-102 Gamma for target practice in Final Egg, as Eggman sends him next after E-101 Beta has been practicing in the shooting range. During the Action Stage, there are many Tails and Knuckles dolls, while only one Sonic Doll can be found, hanging on the shooting range at the end of Gamma's section. Destroying Tails and Knuckles Dolls will give extra points for the timer. Gamma completes the Action Stage by shooting Sonic Doll three times. These dolls do also appear in Sonic's version of the Final Egg as a desperate attempt to stop the hedgehog.
In Sonic Rivals, all three dolls from Sonic Adventure are featured as their own collectible cards.
In other media
In the anime series Sonic X, the Sonic Doll makes a brief appearance and bears a larger resemblance to Sonic himself. They were used by Dr. Eggman to test his new E-100 Series.
↑Stratton, Bryan (17 June 2003). "E-102 Gamma's Adventure Fields and Action Stages". Sonic Adventure DX: Director's Cut: Prima's Official Strategy Guide. Prima Games. p. 109. ISBN 978-0761542865. "Advance to trigger more dolls. If you approach the hall, you can simultaneously target as many as five dolls."
↑Stratton, Bryan (17 June 2003). "E-102 Gamma's Adventure Fields and Action Stages". Sonic Adventure DX: Director's Cut: Prima's Official Strategy Guide. Prima Games. p. 109. ISBN 978-0761542865. "There's no reason to fly to the little island near the point marker and shoot the target dolls there."