Bassnium

"Currently Bassnium is the most powerful energy on Earth."

- Dr. Wily

Bassnium, known as Fortenium (フォルテニウム) in Japan, is the energy that powers Bass.

History
Tired of his constant defeats, Dr. Wily began to study Mega Man, hoping to create a similar robot. During this process, he unintentionally created a powerful energy source which he named Bassnium; he then created Bass using this energy. At the time of the classic series, Bassnium was the most powerful energy in the world.

Mega Man 2: The Power Fighters
After being defeated by Bass, Wily tells Bass about his discovery of Bassnium and his subsequent creation of the former, as well as how he is studying this energy to create a new powerful robot that has more strength than both Mega Man and Bass together. He also talks about his "other project". Bass responds saying that a "girlie-looking, long-haired robot" would never defeat him.

Characteristics
Bassnium is an infinite energy source that provides incredible power output and excellent mobility (However, since the source of this information, Rockman Online, has been canceled, its canonicity is questionable). It is possibly radioactive in nature.

Using this energy source, Bass has shown in several instances to posses the ability to release green or purple energy in the form of an aura that usually suspends him in the air.

Trivia

 * In the English version of SNK vs. Capcom: Card Fighters DS, Bassnium is said to be an alloy in the description of Bass' card. However, this is a mistranslation, as the Japanese version states that it is an unknown energy.