For dual screens and taunt, I’d say Grimmsnarl is better. However, you could run hazards Deoxys.
https://pokepast.es/8cdeae60ee7d8d80
Max defense Grimmsnarl to live a Bblade from Zacian If you use reflect
You only have one other special attacker other than Caly-S, so you could run one of these:
https://pokepast.es/17d35d134a7d7fb2
Scarf speed ties with Ditto, revenge kills other Caly-S efficiently, and outspeeds the whole unboosted metagame bar Ditto and other scarf coats. Trick messes with Chansey, Blissey, Ttar, and Yveltal that will likely switch in, and aromatherapy provides support for the team.
Life orb is an amazing wallbreaker. A 2+ Max Starfall OHKOs Defensive yveltal, and has a chance to OHKO Ttar. Darkceus gets OHKOd or has a chance to be, depending on it’s EV spread. Life orb Calyrex can be a highly threatening sweeper when it’s checks like Ditto and offensive Yveltal are down.
If you go for hazards, the rest of the team looks fine. Close combat and wild charge over sacred sword and play rough on Zacian, though, and what are the 30 attack EVs on ditto for?
If you decide on screens, the rest of the team benefiting more from screens would be helpful
https://pokepast.es/d7e4820963dfe63f
Xerneas becomes deadly after Geomancy, especially in NDAG where it can hit Zacian and NDM with HP fire. Screens further bolsters this, as it’s harder to revenge kill.
NDM is already pretty bulky, and screens make this better, letting it get up some Ddances. Weakness Policy gives it even more boosts, and prism armor and screens make super effective moves weaker. Dynamax is amazing, as it can get Defense and SpD boosts from Steelspike and Quake. Stone Edge kills Ho-Oh which otherwise is the best check to you.
Pdon, similarly to Necrozma, has huge bulk and can get boosts from it’s boosting moves. Stone edge beats Ho-Oh and flyings, and Precipice blades is STAB, and these two give you the awesome coverage of rock and ground.
https://pokepast.es/2f04bb589021f106
You could also substitute some of those for these, two awesome sweepers with screens. Also, a weakness policy would be nice on Zekrom too.
