Okay, this is one of a number of one-shots that may eventually become a full fledged story. It depends how popular it is, so if you want to follow it if it does become one then fav or alert it. Consider it a 'backburner' story. Or if you wanna take up the story for yourself, go ahead. Just send me a message so I can follow yours.
Robotnik watched. His universe-breaching spy-bot had been a success, in a sense. While he had not found any allies in the otherworld, or at least any he considered worthy of working alongside him, there were heroes to watch. The doctor was reviewing footage taken over the last several hours sent in the most recent log of this 'Mushroom Kingdom Zone.' It was fascinating.
He had considered trying to take over there, but with all the powers at the heroes disposal, it seemed even less likely than succeeding on the planet he was currently on. And still, Robotnik found a use for the video. For the greater part of three months, he had let Metal Sonic do his bidding while he focused intently on a new project. If it's projected abilities held true to reality, then the bane of his existence would finally find a resting place six feet under. Underground or underwater didn't matter, so long as he wouldn't make a triumphant return.
His chair rotated, and he stood next to the workbench that housed his latest project. Nuts and bolts lay around the mechanical beast like spare change. There was a dilemma. Metal Sonic was more effective than some of his counterpart mechas, and it gave him a headache. Originally, he had assumed giving additional capabilities to a version of Sonic would give it the edge. However, since it operated with the same parameters as a Metal Sonic version, only with tied in weapon systems, it's performance went down. Eggman assumed this was because they were programmed to fight with the same style as the hedgehog, which these additional abilities did not include. Yet his Metal Sonic units, despite better field results, still went unable to destroy the blue pest. No version of this hero seemed adequate to trounce the blue hedgehog, and this new data he had been collecting gave him a new idea.
Hours of labor went into his new machine. Despite being a copy of the extra-universal hero, Robotnik had decided to give the project a 'Mecha' designation. He figured that, with its wide range of abilities, it deserved it. Nowhere to be found on it, though, was an ability that the original hadn't had during any of his quests. It worried him, as to how his latest project would deal with Sonic's speed. But he had confidence in the AI that he personally created to mimic the other-hero, who had overcome every obstacle, like his blue counterpart.
"Finally. All that's left is to upload the analyzed combat data from the drone..." His voice was filled with malicious excitement, fawning over his latest dark creation. A large cable came down from the ceiling, and the doctor grabbed it. As it approached the top of the 'head,' a panel opened to reveal a data port. He plugged it in with evil precision, a large grin on his face.
"And to give it a... personal touch." He had sent a second breaching device in order to extract a particular item he found useful. It was like a temporary chaos emerald if absorbed, but he had other plans for the yellow star. It was the final component of this fully functional mecha project, and the central hub of artificial thought, more powerful a processor than anything even he could build. The screen flashed.
"Data upload completed. Brilliant! Finally, I have achieved the perfect instrument to be rid of that infernal pest forever!" He rotated the bench up, and the project began to carry its own mass, focused on a pair of brown, metal boots. Shining blue legs contrasted with the Eggman Red of its 'shirt' and upper head, a powerful helmet designed to protect the Mecha's head from high speed spin attacks. The white panel came down on the helmet, protecting the data port. The helmet itself lowered to a point nearly blocking its optical sensors, securing with interior fastening pins. White 'hands' revealed themselves as the securing arms of the table retracted, letting it stand for the first time as its own entity.
"Engage primary systems, Hyper Mecha Mario!" Red eyes activated, and the whir of its interior mechanics emanated soft sounds that seemed to reverberate through the lab. They then became unhearable as the doctor laughed violently, a hint of success in his evil chuckles.
"Prepare for combat testing, HMM. Lets see how soon you'll be field ready." It stepped down onto solid ground, the step seemingly taking the planet out of orbit.
His master smiled.