I know this is super obvious, but I really hope they have Zacian be a fast physical attacker and Zamazenta be a bulky tank. I know they usually like to have the box legends have inverted stats of each other, but in this case, I think they should make them serve their functions. Or they can have Zacian have high attack and slighter lower special attack and low defenses, then invert it for Zamazenta. So for example:
Zacian: 100/155/95/140/90/100
Zamazenta: 100/95/155/90/140/100
As for typings, I hope for the following:
Zacian: Steel/Ice, Fighting/Ice, Steel/Water, Fighting/Flying
Zamazenta: Steel/Fire, Steel/Ghost, Steel/Fairy