As far as i'm concerned, every Hyperion is an Eternal, in some way. The original Hyperion is from Earth-712, where he's an Eternal. Then, the Grandmaster took inspiration from the 712 one and found a similar Eternal in the Microverse (Earth-616) who is called Zhib-Ran and copied his genetic template to create the Earth-616 Hyperion, who tecnically isn't an Eternal, but a clone of a Microverse Eternal. In recent times, another Hyperion showed up, the one with the black suit. He comes from an alternate reality where he followed the path of the 712 one, but his reality was destroyed and AIM of Earth-616 brought him to them. There's another reality, the Supremeverse (where "Supreme Power" takes place) and this Hyperion has a different look from the previous, but he's in fact an Eternal. So, the main Hyperions are all Eternals and their power derives from the way they use their connection to the Cosmic Power: they create a sort of nuclear reaction within their body to produce the energy they need, and they discharge it in form of Super Strenght, Optic Blasts, Flight...