Umbreon
Offensive Darkinium Z with 3 Normal type attacks? Really? Umbreon has 65 Attack and 60 Special Attack. Normal type moves suck without the STAB boost, especially Quick Attack. Umbreon is not at all good in AG even as a defensive Pokemon. Yveltal's 131 Attack and 131 Special Attack are twice that of Umbreon's pathetic offensive stats, and its offensive movepool is actually good. You can always go defensive as well. All of these traits make Yveltal the best Pokemon in the metagame.
Yveltal @ Life Orb
Ability: Dark Aura
EVs: 4 Atk / 252 SpA / 252 Spe
Mild Nature
- Dark Pulse
- Oblivion Wing
- Heat Wave
- Sucker Punch
Yveltal @ Heavy-Duty Boots
Ability: Dark Aura
EVs: 252 HP / 4 Def / 252 SpD
Careful / Calm Nature
- Snarl / Knock Off
- U-turn
- Roost
- Defog
Lugia
That Lugia set is...extremely strange. It's not like you'll be needing Lugia in the first place. Lugia only fits on hardcore stall teams. This is not a stall team. Calyrex-Shadow is much, much better than Lugia offensively (165 special attack vs 90 Special Attack). It has so much versatility, power, an incredible STAB move, and is just overall immensely threatening. There are several sets it can use, but my personal favorite is QuickPass.
Calyrex-Shadow @ Ghostium Z
Ability: As One (Spectrier)
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Astral Barrage
- Nasty Plot
- Baton Pass
- Substitute
Incineroar
Incineroar is terrible. You have a total of 3 Z-moves on this team (I haven't the slightest clue as to why this is the case). Something you should note is that except for rare cases like Mega Rayquaza and Yveltal which appreciate Life Orb's extra power boost, you should always run Heavy-Duty Boots on Pokemon that are weak to Stealth Rock. You're better off replacing Incineroar with Primal Groudon, who has a nice typing, a Stealth Rock neutrality, and more power, speed, and bulk. However, your team will appreciate Ho-oh's support more. Why not Zacian-Crowned?
Zacian-Crowned @ Rusted Sword
Ability: Intrepid Sword
EVs: 4 HP / 252 Atk / 252 Spe
Adamant Nature
- Behemoth Blade
- Close Combat
- Wild Charge
- Swords Dance / Assurance
Rayquaza
Why Haban Berry? Mega Rayquaza is already resistant to Electric during the strong winds summoned by Delta Stream. I see absolutely no point in running Haban Berry over Life Orb. Mega Ray can either run a Dragon Dance set that demolishes unprepared teams or breaks a massive hole, or a mixed set which lures in common counters to the fully physical set (like Zygarde) and destroys them with Draco Meteor.
Rayquaza-Mega @ Life Orb
Ability: Delta Stream
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Dragon Ascent
- Extreme Speed
- Dragon Dance
- Earthquake
Rayquaza-Mega @ Life Orb
Ability: Delta Stream
EVs: 252 Atk / 4 SpA / 252 Spe
Lonely Nature
- Dragon Ascent
- V-create
- Draco Meteor
- Extreme Speed
Ho-oh
You can keep Ho-oh but the set is...let's just say it's very suboptimal and likely won't get you anywhere. Heavy-Duty Boots, once again, are very important. Unlike Mega Ray and offensive Yveltal, who take 25% from Stealth Rocks, Ho-oh takes a whopping 50%. There is no excuse to run anything other than Boots on a Pokemon that is 4x weak to Rock. I really don't understand why you're running Ancient Power and Scorching Sands. Air Slash is also pretty bad. Ho-oh likes to focus on defense more, as it has a lot of nice attributes like a 50% burn move, Regenerator, and Defog.
Ho-oh @ Heavy-Duty Boots
Ability: Regenerator
EVs: 248 HP / 208 Def / 52 SpD
Impish Nature
- Sacred Fire
- Toxic
- Defog
- Whirlwind / Roost
Ash Greninja
Once again, Quick Attack sucks (you have both STAB Shuriken and Quick Attack?) and running 3 Z-move users is also bad. If you're thinking Primal Kyogre, it isn't very good. Arceus-Water, however, is a viable bulky Water type, since it can check many common Pokemon like Arceus-Ground, Necrozma-Dusk Mane, and defensive Zygarde and Primal Groudon. Your team lacks a reliable Zacian-Crowned check (notice how I said reliable. Primal Groudon resists Behemoth Blade but is 2HKOed by Close Combat after Stealth Rock and has no recovery outside of Rest). Necrozma-Dusk Mane is the best Zacian-C check. It has reliable recovery in Moonlight/Morning Sun, a Stealth Rock resistance, and the freedom of running whatever item it wants. It can run Leftovers for more recovery, Rocky Helmet to punish Zacian's moves and to chip it until it is in Sunsteel Strike / Earthquake KO range, and Heavy-Duty Boots to foil Assurance Zacian-C with Stealth Rock + Spikes up, which has popped up almost solely because of Dusk Mane's prominence.
Necrozma-Dusk Mane @ Leftovers / Rocky Helmet / Heavy-Duty Boots
Ability: Prism Armor
EVs: 252 HP / 252 Def / 4 SpD
Impish Nature
- Sunsteel Strike
- Morning Sun / Moonlight
- Stealth Rock
- Knock Off / Earthquake