From experience when I played you on ladder this team is super weak to Mega-Gar + literally anything. Making lando or lele scarf would go a long way imo.
I wanted to build a team with Alolan Ninetails and ended up liking the results. Aurora Veil is a super neat move that makes hail viable imo. This team works well as a solid Magearna/Zygarde CT without being unviable in other matchups. Most notably I've won multiple games against other people using SamVGC's "Protek the snek" team and variants of it (replays below). Psychic Seed Milotic is a pretty big threat though, so take out that mon ASAP if you face it. Opposing weather teams also make it harder to set Aurora Veil.
Landorus-Therian @ Assault Vest
Ability: Intimidate
EVs: 112 HP / 156 Atk / 16 Def / 4 SpD / 220 Spe
Jolly Nature
- Earthquake
- Rock Slide
- Knock Off
- Superpower
Tapu Lele @ Psychium Z
Ability: Psychic Surge
EVs: 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk
- Psychic
- Moonblast
- Taunt
- Protect
Jirachi @ Safety Goggles
Ability: Serene Grace
EVs: 252 HP / 92 Def / 164 SpD
Bold Nature
IVs: 0 Spe
- Follow Me
- Iron Head
- Trick Room
- Protect
Ninetales-Alola @ Light Clay
Ability: Snow Warning
EVs: 252 HP / 4 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Blizzard
- Moonblast
- Aurora Veil
- Protect
Volcanion @ Shuca Berry
Ability: Water Absorb
EVs: 4 HP / 252 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Heat Wave
- Steam Eruption
- Earth Power
- Protect
Salamence-Mega @ Salamencite
Ability: Intimidate
EVs: 252 Atk / 4 SpA / 252 Spe
Hasty Nature
- Double-Edge
- Draco Meteor
- Earthquake
- ProtectReplays:Lando: Standard AV Lando set. AV stacks well with Aurora Veil to let Lando take hits really well. The Intimidate support and ground coverage help against Mage and Zygarde teams.
Tapu Lele: The best Tapu. EVs let it hit hard and fast, letting it outspeed neutral base 100s like Adamant Kangaskhan. Tapu Lele's main goal is to hit hard with terrain-boosted Psychic attacks and nuke stuff with its 175 bp Shattered Psyche. Moonblast is additional STAB coverage to hit Dark types. Taunt is a layer of defense against Trick Room teams. It can also disable Jirachi's follow me, but be wary of getting an Iron Head in return.
Jirachi: Obligatory bulky steel / redirector. I kept Goggles on Rachi because it protects it against hail chip damage, and things like Mega Venusaur or Amoonguss could still try to sleep your team. Trick Room > Icy Wind to reset TR against setters, but that's just my preference since this team otherwise lacks TR checks.
Ninetails-Alola: I'm torn on what to run for EVs here, but for now I'm running max HP and max+ speed. The main purpose of Ninetails is to set Aurora Veil, which reduces the damage your team takes from all attacks by one third (it's like duel screens in one move). Light clay lets Aurora Veil last for 8 turns. Dragons and Lando don't want to stay in on Blizzard, and Moonblast can hit dark types like Scrafty pretty hard. If I can figure out specific offensive benchmarks, I might try investing more into special attack.
Volcanion: Max+ speed and max SpA let it outrun Modest Heatran and ensure it gets the jump on Magearna. Shuca Berry helps it stay in on a ground attack - especially when Aurora Veil is up. Pretty standard set overall.
Mega Salamence: This is basically a standard physical Mence set, but I went Draco Meteor > Dragon Dance to let it ohko opposing Dragons and take a good chunk out of Zygarde.
[Gen 7] Pokebank Doubles OU: not haruno vs. GenOne (fwiw I did lose in a rematch)
[Gen 7] Pokebank Doubles OU: Sexual_Blaziman vs. GenOne (also lost in a rematch)
[Gen 7] Pokebank Doubles OU: GreenGogoatttt vs. GenOne