Necrozma-Dusk-Mane @Weakness Policy
Ability: Prism Armor
EVs: 4 HP / 252 SpA / 252 Spe
Jolly Nature
- Dragon Dance / Autotomize / Rock Polish
- Sunsteel Strike
- Stone Edge / Prismatic Laser
- Earthquake
Explanation:
Since all of your weakness is just 1.5x Damage, Weakness Policy is a nice item to use.
First move; a speed-boost. No matter if you move first or not.
Proceed to use any move, depends on effectiveness.
Necrozma-Dawn -Wings @ Weakness Policy
Ability: Prism Armor
EVs: 4 HP / 252 SpA / 252 Spe
Timid Nature
- Rock Polish / Autotomize
- Moongeist Beam
- Stored Power
- Heat Wave
Explanation:
It's more difficult to use a set with this form. As your only 2 weaknesses are 3x damage, you wouldn't want to wall that. But who cares if it works anyways.
Use a speed-boost move, then spam Stored Power or anything else. Activating Weakness Policy is a better thing (If you survive the hit, that is.). It allows your Stored Power to have 140 Base Power (it's also STAB).
Necrozma @ Petaya Berry / Weakness Policy
Ability: Prism Armor
EVs: 4 HP / 252 SpA / 252 Spe
Timid Nature
- Stored Power
- Autotomize
- Earth Power
- Heat Wave
Don't forget, Necrozma can now learn Heat Wave. Earth Power and Heat Wave cover a lot of types. Then just spam Stored Power for the rest of the enemies who can't resist/aren't dark type.
They all have the similar strategy.
Speed Up, then Spam Stored Power.