Solgaleo vs. Necrozma Dusk-Mane:
Comparing their stats, Solgaleo has better HP, Speed but lower Sp.Def and Atk than Dusk-Mane. Regardless of Dusk-Mane's slower speed, it can learn Rock Polish and Autotomise, while both of them can learn Trick Room, Solgaleo had disadvantage of having only Flame Charge to increase its Speed. Also, Solgaleo's average Sp.Def means it can not necessarily survive a SE special attack. Apart from that, both have a similar moveset like getting Earthquake, Stone Edge, Morning Sun, etc. The biggest advantage Necrozma apart from Ultra Burst is because of its ability. Prism Armor is much more better than Full Metal Body because SE attacks are much more common than Stat lowering attacks. Necrozma Dusk Mane can also take advantage of its ability to trigger Weakness Policy, then just Autotomise and sweep teams away.
Judgement: Necrozma Dusk Mane wins.
Lunala vs. Necrozma Dawn Wings:
Here's what Smogon says about Dawn Wings:
At a first glance, Necrozma-DW may seem like a more powerful wallbreaker than Lunala. However, numerous factors undermine Necrozma-DW's effectiveness to the point where there are barely any viable options for it to use. Necrozma-DW lacks Shadow Shield, and combined with its low Speed and lack of resistances, it is vulnerable to almost every offensive foe that outspeeds it. Prism Armor does not alleviate Necrozma-DW's extreme weakness to very common threats like Yveltal, Mega Gengar, and Marshadow at all, and its lack of usable coverage moves leaves Necrozma-DW with only a few foes that it can defeat.
For these reasons, Necrozma-DW is an unviable Pokemon in the tier.
Source
Here you go. It made clear that Dawn-Wings should only be used as Ultra-Necrozma. Apart from that, both mostly share a moveset. The 4x weakness of both should not be underlooked. However, due to Lunala having Shadow Shield makes it really good plus its speed of 97 is decent. While Dawn-Wings 4x 2 weakness are bothersome despite Prism Armor making it do 3x damage, it also has bad speed.
Judgement: Lunala wins.
Sets
Necrozma Dusk-Mane:
Necrozma-Dusk-Mane @ Weakness Policy
Ability: Prism Armor
EVs: 252 Atk / 100 Def / 156 SpD
IVs: 0 Spe
Brave Nature
- Photon Geyser
- Sunsteel Strike
- Stone Edge/ Earthquake/ Rock Blast
- Trick Room
Lunala:
Lunala @ Heavy-Duty Boots
Ability: Shadow Shield
EVs: 252 HP / 252 SpA / 4 SpD
IVs: 0 Spe
Quiet Nature
- Trick Room
- Moongeist Beam
- Teleport
- Moonblast
