Here is a long sleeve Jean-shirt with embroidered Sonic and Sega logos. As you can see, it's a button-down with a pocket. All that is known is that something to do with Hilton produced it. This shirt is not common.
Photos courtesy of GreatThings4U.
This shirt uses an actual level-design as the background. The colors are tinted from the game, though. They've even left the scores in, which is a strange touch. A stock Sonic jumps over a retractable buzz-saw in the Scrap Brain Zone. This shirt is also uncommon. It has a UK slight variant version of it.
Photo credit to GreatThings4U
This shirt is by Signal Activewear.
It is unusual, in that it actually features a scene on it with a real background. You can see Robotnik/Eggman in his pod, with part of a zone. The Sonic graphic is nice, but poor Tails is shorted by looking mutant in the face. This is a rare button-down. The rather unfortunate plaid sleeves do not particularly mark it as 'activewear' but...it's a good one to collect still.
Photo credit to GreatThings4U
This is an extremely popular yet scarce shirt. The design is highly coveted. The slogan says "Sonic Blue 'em all away!" which is a fairly ok pun (are puns really ok?) but the large shadow and well-done stock art make this one of the top early designs. As you can see, a mini-art copy decorates the top-back.
It was available for a short time in a SegaWear catalog. This is more like a full-color folded leaflet that came with a few Sega games for a period of a few months. Other Sonic clothing items found on these pages were in it as well as SegaSports themed things. Because the catalog wasn't always available, and the merchandise seemed in short supply, this shirt and some of the other items are scarce.
Photo credit to GreatThings4U
An ancient stock art Sonic stands in front of the SEGA logo, and on top of "Sega Channel". Was there really a Sega Channel? If so, it was quite short lived, and had to of occurred at some point in the 1990s. This shirt isn't common either.
Photo credit to GreatThings4U
This gray shirt is rather classy for the times. A band of actual well-done Sonics runs across the bottom among rectangles and logos. It says "Sega" and "Sonic the Hedgehog" along the band at he bottom. There is a small "#1" at the top, which almost seems out of place among the other bold items.
This shirt is barely on the edge of classic. It occurred right before Sonic Adventure 1. The stock art is nice, and "Sonic Sega" are written in a convincing stone textured font. The print quality is good, and it came in a size you can actually fit into.