Tails Doll
From Sonic Retro
The Tails Doll (also mistakenly called "Puppet Tails") is a secret character in the game Sonic R, unlocked by finding the 5 tokens in the "Radical City" track and finishing 1st, 2nd or 3rd in the race. Tails Doll has poor handling, average acceleration and average top speed. Its jumping abilities are quirky, too, since it cannot jump very high, but seems able to float as it can glide over water in the courses. It is also the only character who can float over the water without slowing down after a period of time. If you are not playing as the Tails doll and you beat him, sometimes it looks like he is bleeding (though it is just his shoes).
Tails Doll seems to be one of Dr. Robotnik's creations. Sonic R features metal versions of Sonic and Knuckles. This is likely due to the fact Metal Sonic had long been established as one of Sonic's most deadly foes. However, in place of a "Metal Tails", there is the Tails Doll, an unusual move. Tails Doll was most likely created by Traveller's Tales, the team that worked on Sonic R. This likely explains why he has not yet appeared in another Sonic game. Although similar characters appear along with Sonic dolls and Knuckles dolls in Sonic Adventure DX: Director's Cut as targets in E102's first level), these Tails dolls had no red jewel on their forehead.
It is also possible to assume that Tails Doll was designed as a joke character due to all the other Robots being designed as real threats (with the exception of Eggrobo who is the only existing Badnik to appear in Sonic R). Its appearance is as mysterious as the character, and many people wonder about the strange jewel on its forehead that it supposedly draws energy from. This has not yet been verified, and probably never will be, for SEGA and SONIC TEAM have not used Tails Doll in any further productions.
There have been other sightings of this strange character. In one the original Adventures of Sonic the Hedgehog cartoons, Robotnik's Minions dress up as Tails's long-lost parents to fool him. One has a zip down the back, as Tails Doll does, and the antenna sticks out the top, rather like the jewel on Tals Doll's head.
It is assumed that Tails Doll and Metal Knuckles did not, unlike Metal Sonic, gain sentience and therefore would likely have been deactivated by Robotnik or destroyed by Sonic, whereas Metal Sonic appears to have gained a sort of will to live. It is unlikely Tails Doll will appear again in the series. Many fans have assumed Tails Doll was once used as a decoy to fool Sonic in the place of the real Tails, through no published media or games have supported this theory.
Tails Doll is a little-known character because Sonic R was released in the late years of the Sega Saturn. This character has a small following among Sonic fans due to its supposed "creepy" look in comparison to its robotic counterparts in the game (Metal Sonic and Metal Knuckles). In many fanfiction projects, the Tails Doll is supposedly able to materialize and slaughter, possess, enslave, or suck out the souls of those who complete Sonic R or tag Super Sonic as Tails Doll.