Quoted By:
The Ultra Beasts are pretty clearly based on planets/the gods the planets are named after. Though I never bothered to research all the details, once I got the gist of it.
>solgaleo and lunala are sun and moon, zygarde which is not a UB but whose ultimate form came out in sun and moon represents the earth
>mercury is the greek messenger god, he flits between the world of mortals and the world of the gods
>alchemic mercury is the "first metal from which all others being"
>niheligo is the first being from ultra space you encounter
>pheramosa and buzzwole being venus and mars are fairly self-evident
>xurkitree is all about electricity
>the greek counterpart of jupiter is zeus
>the god saturn was a god of agriculture, and his iconic symbol was the scythe
>kartana is a grass type with blades
>celesteela is based on some sort of japanese moon legend thing, but it's ALSO a flying type and heavily based on a rocket ship
>uranus is the greek god of the sky
The only one I never sorted out was Guzzlord. Presumably it represents Neptune, but I could never find a connection. I don't think the new UBs in Ultra Sun and Moon follow the same theme, or know where Necrozma fits into this, but who knows