So, in the old days of Bionicle, it was established that there was such a thing as "Inner Light" and "Inner Shadow."
I imagine that these were just terms for morality, and that every being in the Bionicle World, MU or not, has them. That is to say, Agori, Glatorian, and even the Great Beings have them.
However I theorize that in the MU, the way their biology/mechanics are, that these thigns are tied to elemental powers, as evidenced by Makuta(Melding), Roodaka, and others.
While it is established that a Makuta can attain Light Powers by ridding themselves of Inner Shadow, and that other beings can gain Shadow Powers by ridding themselves of their inner light, could it be possible to gain Light Powers as well, in other MU Beings like Vortixx or Toa?
Think to Toa Lhikan. His fire power was so...controlled, so orderly that it resembled a laser. A Light power. While I'm not saying that Lhikan has full Light powers, I'm saying that maybe his having Fire Powers correlates to Light and Shadow more so than other elemental powers.
Fire, like Light can be a force for Illumination, and Lasers. However, when corrupted, like by Lehrak or something, it becomes aggressive, and destructive like Shadow(well, Bionicle Shadow. Not actual Shadow)
So I propose that perhaps, perhaps, two things could be possible:
A Being could be created or engineered with Elemental Shadow, but not Fundamental Shadow.(I would call Natural Matoran of this type Kra-Matoran, as opposed to Shadow Matoran)
A being with Elemental Fire Control(Skakdi included) could meditate away his Inner Shadow and gain partial Light Powers, like how some beings can attain partial Shadow Powers.
I'm sure these theories have been Jossed in the past, but they're both headcanons for me personally, as evidenced by my Self MOC.