Roboto is a member of the Heroic Warriors who just happens to be a robot. In most fictional cases Roboto was made by Man At Arms. However in the original cartoon he hailed from a planet named... wait for it... Robotica and crashed landed on Eternia. Where he was then repaired by Man At Arms. This may account for the weapon arm gimmick.The man has a thing for arms after all.
Roboto is pretty freaking awesome. He's got the weapon changing arm gimmick giving him an axe, laser gun, or claw. Regardless of the fight, he has just the tool to whoop that ass! Roboto also has a clear chest which displays his robotic innards consisting of several gears and a heart. Twisting the figure at the hip makes the gears turn and the heart raise and lower. But wait, there's more! Roboto's robot mouth also opens and closes when this is done.
What's not to love about everything I just described?