Very weird because they're too humanoid. Pokemon in Gen 1 were mostly animals and fantasy creatures/youkai, not things that looked like human experimentation gone wrong.
This thing would not be out of place in an indie horror game that some popular Youtuber plays to farm clout/views by having outlandish reactions. Would probably result in some kid's ipad being taken away...
These three Ultra Beasts are creepy good tho! The resemblance to Lillie, Lusamine and Guzma is so uncanny and it's never quite explained why (in game, at least).