E-10000B is a blue robot that appears in Sonic Free Riders as a playable character in Team Dark's storyline. He appears to be on the same frequency as E-10000G. He also replaces Omega as Team Dark's power character. Near the end of the game, he is revealed to be Metal Sonic in disguise.
Shadow and Rouge have just come for the World Grand Prix and attempted to join. However, Omochao refused because they needed three members in order to participate. Rouge then randomly picked E-10000B who agreed to join their team. After a little while, E-10000B complained that he was tired, but was selfishly ignored by his teammates. Later on, E-10000B malfunctioned, broke down, and appears to explode. This exposed him as Metal Sonic. It is unknown if E-10000B was a disguise for Metal Sonic or if Metal Sonic somehow got inside and took control of him.
Rouge the Bat
Rouge the Bat is E-10000B's teammate along with Shadow. Rouge first found E-10000B in Frozen Forest and asked him to join her and Shadow.
Shadow the Hedgehog
Shadow the Hedgehog is E-10000B's teammate along with Rouge. Shadow complimented him by saying, "Well, for a random robot we picked up of the street I'd say he's doing pretty well."
Cream the Rabbit
Cream the Rabbit was worried about E-10000B breaking down. She also got angry at Shadow and Rouge for calling him a "junk-heap" and a "dead-weight". Also, Cream was shown to be caring towards E-10000B.
Knuckles the Echidna
Knuckles the Echidna told Omochao that he saw E-10000B make the clicking sounds and moving funny-like. In addition, Knuckles is shown to dislike E-10000B.
Storm the Albatross
Storm the Albatross once talked to E-10000B, but he did not say anything in response. When Wave then called him a machine, E-10000B got angry at Wave and said, "I'm no machine! I'M A ROBOT! It's different", prompting Storm to get angry at him.
E-10000B is the only character in story mode to not be playable in multiplayer mode, being replaced by E-10000G.