Here are 6 classic pin buttons that could only be aquired at Tokyo Joypolis.
They are all the same size & round. Were they a set, or individual to get? That's unknown. But here you can see a Sonic portrait green on magenta that's...poorly contrasting. Sonic line art with an arrow that says something, but you can't read it because the photo is too small. A plain 'sega' logo button, another Sonic line art portrait with "Segasonic the hedgehog" written under it, a less-common forward punch/leap Sonic in a concentric circles background,
and a more traditional shaded art with "Segasonic the Hedgehog" around the border. It's likely these were all get-able at the same time, and are thus all early works.