>>28476091Pokedex is advanced technology for humans, but it's designed to analyse data from Pokemon, not Ultra Beasts, as we know a lot of pokemon have some sort of genetic base from Mew or Mew's legendary predecessors.
They could be an all different sort of life altogether. An anomoly in space-time. Creatures that physically shouldn't exist but do because they can somehow bypass laws of reality and travel interdimensionally.
The real question is why are Humans not recorded as Pokemon as well? I guess they filter themselves from the dex or something. The series has never outright explained how humans are different from Pokemon and their origin.
(Though they have told of things like poke human relations and ancient human tribes living in codependent lifestyles)
But again, that's not to say Ultra Beasts don't share similarities to pokemon. As i said they could be what Pokemon's and/or humans evolved into in another reality where the rules are different.
They could just be ultra adaptive shapeshifters that adapt their form based on their individual personality, the perceptions of creatures around them and required role they are comfortable with.
There not enough info to tell yet. Im really just speculating because it's fun.