The plot is that a team of 3 people a girl, a boy, and a short man with a funny haircut control robots and fight against a white alien that too can control robots. In the beginning I remember there was some kind of a test that a lot of people came and the prize was a strong mecha. The style was western-style animation.
The short guy in childhood was rescued by a man who controlled a mecha and the short man was amazed. He decided to be a pilot too but because he was short he could only be a guardian. The boy passed something like a test and he trained in organization area.
I remember there was an episode that showed how the alien came and was beaten by a primitive human who could control a bone robot.