>>44884729I'm just going to pretend that this is Unova's original dragon, as well as the "King" mentioned in Abyssal ruins. Both Resh/Zek tails reference electric generators, and can easily just relate to electric polarization.
So when it splits, one head becomes each of the Tao trio, the final head having no protons/electrons left became the neutron shell known as Kyurem.
Also, OP suck it up and use Dracozolt or M-Ampharos on a past gen.