Robo-Robotnik was from an alternate reality where he was defeated by Sonic and Cyborg Sonic and was forced to upload himself to a space station, he waited on the station with no purpose, jst waiting for te battery to run dry.
Eventually Robotnik prime accidentally came aboard the station and managed to perusade Eggman that there was still hope for him, Eggman then proceeded to build a new body for himslef and nuked Mobotropolis, killing Sonic and the other freedom fighters.
After hearing about Robotnik Prime's death, Robo-Robotnik headed to Mobius Prime to defeat Sonic. Though Snivley helped Sonic defeat Eggman, Robo-Robotnik built a new body for himslef and began calling himslef Eggman, he also forced Snivley to aid him. At one point he could roboticize with a touch. He was later De-Roboticized by the Bem.