Meaning in Pokémon Sword, you will battle Zamazenta before being able to catch Zacian, and vice versa for Pokémon Shield. No matter what, you can't catch the other version's legendary Pokémon ...

but perhaps even more interesting is how that opens the door to MH Wilds adapting other legendary Pokemon. The boxart legendaries for Pokemon Sword and Shield, Zacian and Zamazenta, would work ...