Ken Sugimori did not approve of the Ultra Beast designs for regular Pokémon.

Omura also responded to a fan theory that the Ultra Beasts were meant to look distinctly un-Pokémon-like, as if they broke the “rules” of what usually constitutes a Pocket Monster, and Omura said that ...

It isn't the Ultra Beasts' fault that they're so abnormal. Understandably, it seems that Pokemon become unpredictable when ...

Riffing on a recent X theory about the Beasts' design origins, Omura explained that the Ultra Beasts' unusual look stems from ...

Ohmura went on (as spotted by Automaton) to explain that the Ultra Beast designs were actually based on previous Pokémon designs that Ohmura had submitted but had been rejected by primary Pokémon ...

A Pokémon veteran has confirmed that Sun and Moon's Ultra Beasts were based on rejected Pokémon designs.