The Big Bad's identity
A major part of the plot is trying to learn the Big Bad's identity, which remains a mystery, but the nature of how he's kept a mystery would lead one to believe that it would have to be someone who has some connection to Ryan or maybe a character who turns out to be a Chekhov's Gunman:- Godfrey: He hates Mech-X4 with a passion, trying to discredit them, and it doesn't look like he's going to ever see Mech-X4 as a hero. With that said, it's definitely the Mastermind's desire to put an end to the robot, and that would sound like something Godfrey would want.
- Jossed. The Mastermind was Seth Harper. Godfrey loathed MECH-X4 but ultimately had nothing to do with the people actually trying to stop the robot.
- Ryan's Father?: Ryan learns he's adopted, the mastermind already knows the person piloting Mech-X4 is a technopath but doesn't know his name. If the Mastermind is Ryan's father, Ryan's power would be misused, and Leo probably made sure to bring Ryan as a baby away to safety.
- Jossed. Ryan's real parents volunteered for Leo's experiment to make technopaths, but Ryan was the one who actually developed the power. They gave up Ryan for adoption to give him a normal life and keep him safe from Seth Harper.
Ryan will evolve into Mech X-4 in the finale
During the final battle Ryan will either be physically wounded or collapse from overexertion during the fight, and die (could be too dark, but then certainly for a Disney show this is pretty dark). Anyway suddenly Mech X-4 start's moving again and Ryan's voice can be heard and it's revealed that the link between Ryan and the robot meant that at the moment of his death Ryan was backed up to Mech X-4