First, it helps to differenciate between the two energies of MM8 and MM2:TPF, the Evil Energy and the Alien Energy, which is alot like Duo (reading from the ending). Also there we have the polar opposite of Evil energy, namely Justice energy, which is not even in Rockman, but also in Forte as well.
From my observations, Justice Energy appears to be synonymous with the Heart, which is superior to the body. As it takes great courage and willpower to stand in the face of danger, I came to the conclusion that emotions create this Justice Energy. Since Forte doesn't fight for a right cause, he always loses to Rockman, because he only fights for himself. As Rock believes in justice, he will always risk his life to save the others, which requires great courage. If Forte would fight with the mindset of Rock, he too would generate more Justice Energy, which would give him the edge in battles.
Remember Ra Moon? As Rockman dealt the final blow, Ra Moon commented, that he generated the perfect energy. He felt it impossible to accept, that a less advanced robot could do this.
If Justice Energy is created by positive emotions, so must the same be true for Evil Energy by negative emotions. Now it reaches the case, where we have to differenciate more, since energy based on a aligment isn't automatically sentient as the other alien energies.
As said by Duo, the Evil Energy feeds on the evil of others to multiple itself and to corrupt others. Alone that emotions power it up, is a big indicator that emotions are a energy source and based on what emotions we emit, we create those different energies.
This is why, I am calling Evil Energy, Evil Alien Energy, because it feeds on the evil energy inside of others. To differenciate between them helps a lot, as it avoids unnecessary confusion.
It explains that the Alien Energy can become either good or evil (it is thus neutral), depending who inprints his heart on it.
Dr. Right: That strange energy can generate an incredibly strong power. It’s a mysterious energy that can become imprinted by the heart of whoever uses it, for good or for evil. We must hurry and get it back, or else...
Is it really necessary to rename the Evil Energy to help differentiate it from the "Alien Energy"? It is like renaming X to "EX" to distinguish him from "IX". It would probably cause more confusion to new readers who look for info about Evil Energy, as that's how it is referred in-game and in other sources. And "Evil Energy" already says it, it is the EVIL energy, not the neutral "Alien Energy", which also has a different name in Japan. Check the overall I did to the page.
Of note, Ra Moon says more than once that he is a perfect machine, and Wily points that he is the energy source of the New Yellow Devil (as a resource, like Bassnium). He didn't said that he generated the perfect energy, only that an inferior machine should not be able to defeated his perfection.
And there is no such thing as Justice Energy. Duo made that up. Everyone knows the good guys use Energy Drinks and Energy Tanks like the picture! ;P