Other Metagames AG, not quite satisfied

[Scrotom Dex]

https://pokepast.es/0db78cc45008449e

I've gotten to 14 on the ladder with this, but I struggle against stall. I'm also relatively inexperienced and need to learn to read better as well, which I'm working on.
I've tried an awful lot of things, including Scarf or Specs Kyogre, different Arceus (including one with Recover) and Groudon sets, and a life orb, Z-Move, or Substitute on Marshadow, and this is what's worked best for me. Any further advice?

I guess I should explain more:
P-Don is my phaser, physical wall, hazard setter, and answer to Xerneas, Ho-Oh, Necrozma-DM, and many other things I previously struggled with. It can sometimes take out an M-Ray

Xerneas covers many holes otherwise left empty, deal with M-Ray and Deoxys-A, and provides emergency cleric support.

Arceus is usually my lead, provides support, and can take out any P-Don and Necrozma-DM that don't look both ways before crossing the street. It's also my best answer to an M-Ray lead, something I previously struggled with.

Marshadow is my answer to a lot of other things, notably baton pass users. It can deal with a boosted M-Ray as an absolute last resort.

P-Kyogre provides special hits that are otherwise not heavy enough, and can punish switches with Calm Mind.

M-Ray is pretty self-explanatory.

My main enemies are Chansey, Blissey, Ferrothorn, Celesteela, Skarmory, and Lugia.

 

[Kate]

Ok, I'm going to be honest and say that this team is incredibly inconsistent, and just generally bad. Your one defogger can't recover its HP, which means Stealth Rock often stays on the field permanently. I really shouldn't have to talk about why Marshadow doesn't even beat BP and how sash is incredibly bad and unreliable. Groundceus' nature is Serious, which is, not good. Literally any time a scarf pokemon comes in, it claims a pokemon. I would suggest replacing Toxic with Recover on Groundceus, make Marshadow Marshadium Z, and a bunch of other fixes that could be made to this trainwreck of a team. I'd also suggest for you to add actual descriptions, as detailed by this thread.

 

[Scrotom Dex]

Ok, I'm going to be honest and say that this team is incredibly inconsistent, and just generally bad. Your one defogger can't recover its HP, which means Stealth Rock often stays on the field permanently. I really shouldn't have to talk about why Marshadow doesn't even beat BP and how sash is incredibly bad and unreliable. Groundceus' nature is Serious, which is, not good. Literally any time a scarf pokemon comes in, it claims a pokemon. I would suggest replacing Toxic with Recover on Groundceus, make Marshadow Marshadium Z, and a bunch of other fixes that could be made to this trainwreck of a team. I'd also suggest for you to add actual descriptions, as detailed by this thread.

The Groudon is Careful, not Serious. I've already messed around with some of the changes you've suggested, but I'm willing to give them another shot, especially as I only initially tested the changes individually.

So, is this any better:

Groudon @ Red Orb Ability: Drought EVs: 252 HP / 252 SpD / 4 Spe Careful Nature - Precipice Blades - Roar - Fire Punch - Stealth Rock

Xerneas @ Choice Scarf Ability: Fairy Aura EVs: 4 Def / 252 SpA / 252 Spe Modest Nature IVs: 0 Atk - Moonblast - Focus Blast - Aromatherapy - Thunder

Arceus @ Earth Plate Ability: Multitype EVs: 252 HP / 240 Def / 16 Spe Serious Nature IVs: 0 Atk - Judgment - Recover - Ice Beam - Defog

Marshadow @ Marshadium Z Ability: Technician EVs: 252 Atk / 4 Def / 252 Spe Jolly Nature - Close Combat - Spectral Thief - Shadow Sneak - Bulk Up

Kyogre @ Blue Orb Ability: Drizzle EVs: 252 HP / 252 SpA / 4 Spe Modest Nature IVs: 0 Atk - Origin Pulse - Thunder - Ice Beam - Calm Mind

Rayquaza @ Life Orb Ability: Air Lock EVs: 252 Atk / 4 Def / 252 Spe Adamant Nature - Dragon Ascent - Dragon Dance - Earthquake - Extreme Speed

Importable

Groudon @ Red Orb
Ability: Drought
EVs: 252 HP / 252 SpD / 4 Spe
Careful Nature
- Precipice Blades
- Roar
- Fire Punch
- Stealth Rock

Xerneas @ Choice Scarf
Ability: Fairy Aura
Shiny: Yes
EVs: 4 Def / 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk
- Moonblast
- Focus Blast
- Aromatherapy
- Thunder

Arceus @ Earth Plate
Ability: Multitype
EVs: 252 HP / 240 Def / 16 Spe
Serious Nature
IVs: 0 Atk
- Judgment
- Recover
- Ice Beam
- Defog

Marshadow @ Marshadium Z
Ability: Technician
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Close Combat
- Spectral Thief
- Shadow Sneak
- Bulk Up

Kyogre @ Blue Orb
Ability: Drizzle
EVs: 252 HP / 252 SpA / 4 Spe
Modest Nature
IVs: 0 Atk
- Origin Pulse
- Thunder
- Ice Beam
- Calm Mind

Rayquaza @ Life Orb
Ability: Air Lock
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Dragon Ascent
- Dragon Dance
- Earthquake
- Extreme Speed

 

[pulsar512b]

First off, Xerneas should probably run it's standard geomancy set. The changes MDB gave are good as well. The reasoning behind making xern traditional geomancy is because you dont seem to have a clear sweeper and geoxern is easier to use.
I would recommend changing arceus ground to steel so that you have something to deal with fairies more effectively.

 

[Bread Sandwich]

First off, Xerneas should probably run it's standard geomancy set. The changes MDB gave are good as well. The reasoning behind making xern traditional geomancy is because you dont seem to have a clear sweeper and geoxern is easier to use.
I would recommend changing arceus ground to steel so that you have something to deal with fairies more effectively.

Honestly scarf xern is fine, the biggest change I would make if I want to best stall is to run sub bulk up marshadium z and possibly rest on pogre could help if you want to beat stall also I would run recover over either ice beam or toxic on arceus ground, really it is up to you on which on is more important