Plutonians are a sentient species of energetic beings using plutonian matter to take shape and interact with the physical world, they have the ability to go bakc to their energetic form to travel great distances. It is unknown if they need plutonian conditions in order to assume physical shape elsewhere.
Men of Pluto action figures where commercialised in the sixties. Their story was told at the back of their blisterpack:
The cold and desolate planet Pluto is too far from the sun ti derive its heat and, thus, the very atmosphere lies frozen and life as we know it cannot exist. But there, at the very edge of the Solar System, the great intergalactic winds that blow between the stars carry with them great mass of cosmic energy. In the beginning, this living energy bombarding the frozen planet did itself freeze to become living matter and, this, a might race of beings began. created of energy, they can become energy at will and Electron +, from his laboratory in Electra City, can transport himself throughout the universe as a beam of light.