This plush was made by SEGA, and was produced to coincide with the release of Sonic Adventure 2. It is notable, as it is the only plush of Sonic with his Soap shoes.
Here is the full set:
(Source: Official pre-release set image by SEGA)
Interestingly, this plush was re-released in Korea as a pre-order bonus for Sonic Heroes.
(Source: Official promotional image by SEGA & YBMSisa)
It is also known that SEGA still own a large quantity of this plush. They sometimes use it as a prize, or for decoration, at specific events.
SO the poll for Enamel Pins is pretty much over with Sonic winning and Chao coming in second. There were some pretty cool recommendations in the comments too so here's some sketches for a proposal.
I'm only going to pick two of these to finalize for right now, which ones do you think would make cool enamel pins???