So, looking at this team, I can see that you have no real answer Ho-Oh or Kyogre, both of which are fairly common in AG. To deal with this, I recommend dropping Ditto. You already have answers to both Calyrex-Shadow and Zacian-Crowned, the main threats ditto is supposed to revenge kill. Why don't we try Specially Defensive Eternatus instead?
Eternatus @ Black Sludge / Heavy-Duty Boots
Ability: Pressure
EVs: 212 HP / 252 SpD / 44 Spe
Calm Nature
- Dragon Tail / Dynamax Cannon
- Recover
- Flamethrower / Mystical Fire
- Toxic / Toxic Spikes
44 Speed to outspeed non-Scarf Kyogre; the rest are dumped into HP and SpD to best tank its hits. Toxic can cripple Ho-Oh and other walls.
Other minor suggestions:
- Calyrex-Shadow: Focus Sash --> Life Orb
If running Draining Kiss, non-Life Orb Calyrex does not hit hard at all. If you even want a chance at doing anything to Yveltal, Life Orb Max Starfall is the way to go. Sash Calyrex-S is probably better with Baton Pass.
- Yveltal: Lower speed a bit
With U-turn, it's usually better to Slow Turn against other Yveltal. Try either min-Speed Sassy or 25 Speed and neutral-nature.
- Necrozma-DM: Consider changing Knock Off to Thunder Wave
Since Yveltal already has Knock, you don't necessarily need it for Necrozma too. Thunder Wave can better neutralize Calyrex-S or offensive Yveltal that try to switch in on it, as well as slowing down Zacian-Crowned. However, be careful not to paralyze Ho-Oh and other walls without thinking. It's always better to Toxic them.
So those are all my thoughts on this team. Write a comment below if you think I missed something. Hope I helped :)