Yellow Radio being the Yellow King makes him a very powerful and commanding person. He is also very cruel and manipulative person as he was the one who stole the chrome disaster armor and essentially created the fifth one in order to exploit the rules that allows him to kill the Red King.
He along with the Kings of Pure Color attained level nine and decided to create a treaty that seperates their territories and disallowed fighting amongst each other to obtain level ten.
Radio was present when Black Lotus called for the dissolution of the treaty. When her plan was rejected, she beheaded the Red King, Red Rider, to the shock of the other kings, who then attacked her. Lotus went into hiding and hadn’t been heard from for two years. He is also known as the Radioactive Disturber. This implies that his attacks are based around the effects of radiation.