What grasshopper? Sonic CD has Bata-Pyon which is actually a reskinned Splats but I don't remember any from Sonic 2.
I'm surprised nobody here has posted the manga depiction. Here's a thought: what if Little Planet is actually a Dyson Sphere? Or Eggman turns it into one? That would explain why it looks completely metal: it's a shell that surrounds the planet, while everything you see in the game is in the interior with perhaps artificial skies.
The more concept art we have, the more it feels they wrote a basic game design document (Sonic time travels, there's a Mecha Sonic, Eggman gets his own planet-like ship) for Sonic 2 that was intended for multiple platforms, and then each platform became its own separate game built on that skeleton