A curious statement expressed by the dim-witted Ultraman of Earth-Three when he, alongside his fellow Crime Syndicators, encounted Earth-Two's Per Degaon in interdimensional limbo. He said "I'm from a Krypton which didn't explode as it did ns some other universes". And yet, this is the element that gave him additional abilities!
It was on this occasion wherein Ultraman revealed to Degaton that he also had been freed from their bubble-prison in limbo as had Superwoman, Johnny Quick and Power Ring (poor Owlman, he never had his opportunity to return to his homeworld until just prior to the Crisis on Infinite Earths, which had destroyed it!). Bathed in Kryptonite radiation from Lex Luthor's power-glove, Ultraman was strengthened, and it was this same residual radiation that weakened both the golden and silver age Supermen who were visiting his world and engaged him in battle. So the obvious question we need to ask is this: If Ultraman's homeworld of Krypton-Three hadn't blown up, why has he encountered Kryptonite since it is formed from fragments of the exploding planet itself! A supplemental question might well be how it was he ended up on Earth-Three, leaving behind his fellow residents of Krypton-Three? The latter question is easily answered... he is a malcontent and criminal... and their form of punishment was exiling such individuals in space as had been on the other two known Kryptons.
Evidently, we have to surmise one of two hypothesis. The first is that the Kryptonite that ended up in Earth-Three's universe is originally from either Krypton-One and Two, somehow crossing the dimensional gulf and ending up where Ultraman could siphon its energy. This is highly enlikely given the amount of such substance necessary to empower Ultraman for years would necessitate a large quantity of this element, not to mention to drastic cosmic imbalance that that loss of such mass in one universe would have without some compensatory mass in exchange. The second hypothesis which is more likely is that is was synthesized much like that in laboratories on Earths One and Two. Since Ultraman himself did not posses the shear intellect to create such an anomaly, as evidenced by his demeanor versus the Supermen and Luthors, evidently a scientist on either his adopted world or Kyrpton-Three had created this. And since Synthetic Kryptonite was based on the original substance that could come only from the mass of a planet Krypton, this scientist would have had to have been a resident of Krypton-Three (logically, this would have been Ultraman's father Jur-Ll whom we'll consider next). This would indicate that there were potentially millions of superhuman beings, just like there had been on Krypton-Two although able to do more than simply leap tall buildings as had those Kryptonians, albeit not on Earth-Three but Krypton-Three!