you people continue to forget the rightfully justified bond phenomenon/"synchro" speculation that's ongoing and often claimed to be debunked
but it ain't over until release day
there are two instances in trailers where the z move symbol appears on the trainer after they do a certain pose and not on the Pokémon itself, before an odd cutaway in those instances, but it helps support the speculation
anyway
the ultra beasts adopt some physical and perhaps personality characteristics of the 3 blonde characters we can link them to the most
ash greninja does that too (not by much, but neither do they), yet it's still a separate entity as we see ash controlling it in battles
there's a catch that ash feels the pain and can even pass out in that state, but greninja seems to be able to mimic the motions of ash (hello UB-01 description??!)
we can draw an easy conclusion at this point:
yes, ultra beasts in their current form are boss fights and not catchable
but what if it's simply the result an extreme form of a currently unknown mechanic that has long been proposed
character x unknown (maybe legendary?) pokemon undergo unexplained transformation merging them into one and for the convenience of plot, said character and/or Pokémon have little to no awareness of this and perhaps enter a rampage of some nature, resulting in a face off against a totem pokemon-esque boss fight
easy crisis right there guys
the unknown pokemon in question likely can be caught post game where you could pull a controlled version of this off because reasons (see: primals) enjoy your ultra beast (mode)
the catch is it faints and you auto lose like synchro is speculated to do based on ash if greninja faints
one final hail mary in a battle seems to be a growing trend after all (Z moves, megas to an extent)
we've also seen a variant of megas (Primal Reversion) so this isn't that crazy
since when has pokemon had complicated explanations to simple stuff
aliens disguised as humans, really
the writing is on the wall and time is winding down to drop the synchro bomb. WAKE UP SHEEPLE