Technetium is the smallest radioactive element and thus a great exception among its neighbouring elements. It was the first artificially made element leading to its name: the Greek word technētós means "artificial".
Technicus the monster looks like put together from various spare parts. It wants to belong to the "good guys". But because of its radioactivity the other monsters avoid it.
Plutonium is extremely poisonous and highly radioactive. It’s main use is for nuclear enerergy and in atomic bombs. His name patron, dwarf planet Pluto named after the Greek god of the underworld, was chosen wisely.
Pluto is an evil fella. Together with his partner in crime Urano, he plots to take over the world.
Uranium is a dangerous metal. Before it was known for it’s radioactivity, people used it to die glass green. It is mostly used for atomic energy and atomic bombs. His name patron Uranus is named after the god of the sky and the father of all gods in Greek mythology.
Urano the monster wants to be the ruler over all the Elemonsters world. He believes that he’s entitled to it, for his name to begin with. He tries to reach this goal by any means. Be it by creating new monsters with nuclear fusion to form a clone army.