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 and how he is studying this energy to create a new powerful robot that has more strength than Mega Man and Bass together. He also talks about his other project. Bass responds saying that a "girlie-looking long-haired robot" like that would never defeat him.

Characteristics
Bassnium is an infinite energy source that provides incredible power output and excellent mobility. 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, it is a mistranslation, the Japanese version saying that it is an unknown energy.