This little display figure is from 1991, by Tomy. This set of 4 non-posable figures was one of the earliest sets, and each one came on a bubble card. The back (at right) uses line art to show who all was on the line. The Robotnick can be seen on Display Figures 1, also carded. The back view shows just how short the legs are, and that they had an ok grasp of the spikes, but they are rather flat.
The Sonic figure is somewhat primitive, with one big eye and one small one, as well as a bit of big-body, but due to the age and now relative scarcity of the figure, it's quite collectible.
These other figures are also very early models. The Eggman is sort of a cross between Eggman/Robotnik before they decided to change his look in non-Japan countries, so he's especially uncommon.
The Eggman also looks a bit out of scale with the other PVCs, being extra small. The Tails isn't too horrible, though he's nearly legless, and Sonic is shown cheering with both fists up, which is also not that common especially in early merchandise which they tended to base only off stock art. Photos by John.
Photo by John
Photo by John
Photo by John
Photo by John