So the last 2 Gens we've had gender based cover legends. Lunala is more of a enligant, quiet girl but will battle if necessary. Solgaleo is like a rambunctious, loud boy, probably picking lots of fights. but on the other tail, Zacian and Zamazenta don't seem gendered. since I've never played the game, I'm lost on this.
Zacaian's Shield entry:
Some say it’s Zamazenta’s elder sister—others say the two Pokémon are rivals.
So it isn't certain whether they are siblings. It's quite possible they are, but it's also possible that they are merely rivals.
Hope I helped!
Well those two may be inspired by the wolves that hunt the sun and moon in Nordic culture. It is said that the wolf that hunts the moon (Zacian) is more feminine looking while the other (Zamazenta) the one that hunts the sun is more masculine looking because long ago sun = man moon = woman https://www.youtube.com/watch?v=xhffmUJpu0k&list=ULDwTa_Au1LWE&index=511 Check this link out