>>58521256From my point of view, it goes even deeper than that:
For example, Calyrex has already faced Eternatus in the past. He ended up weakened and traumatized. We can draw a parallel with the wolves that have already faced Eternatus and are covered in scars.
The wolves have forms that refer to royalty, and Calyrex is explicitly the former ruler of Galar. It also seems to me that Sonia describes the wolves as the kings of Galar too!
They all have absolute powers: Zacian has the ability to cut through anything, Zamazenta can block anything. And Calyrex is so intelligent that it can see the future, the past, and the present.
The wolves reject Dynamax energy, while Calyrex uses its own energy to use the gimmick (hence the blue color like its psychic abilities).
The official website also described Zacian, Zamazenta, and Calyrex as graceful, majestic Pokémon, etc. It's not much, but it's a nice parallel.
Symbolically, we also have: the king who rules and grows food, and two royal knights who protect the kingdom. Everything to ensure the empire's longevity.
And if the sword and shield were Pokémon, why not the kings too?
I haven't mentioned everything, but they have a lot of themes in common. I think if the DLCs weren't separate from the main game's storyline, the connection between them would be more obvious.
We can also mention Zacian's nickname, “Fairy King's Sword,” which implies that Zacian is royal, or that he is the blade of a fairy-like king (which is not irrelevant for Calyrex).
And in Japanese, Zamazenta's nickname refers to a “Warrior King's Shield,” and kings are often warriors.
In this view, Eternatus is the antagonist that the three would face. Eternatus would still be linked to them, but in a more indirect way.
Then even in the colors, we find the classic green, red, blue.
Everyone is free to agree or disagree, but I like this way of interpreting them. To have a kind of “Royal/King Trio” which is THE theme of Generation 8.