For my third shot at this, I'm taking Robbie Moore's second place team at the Roanoke regionals. Fake PG should be pretty hard to screw up...let's see how badly I do.
Tapu Fini @ Wiki Berry
Ability: Misty Surge
Level: 50
EVs: 252 HP / 252 SpAtk / 4 SpDef
Bold Nature
-Muddy Water
-Moonblast
-Protect
-Soak
As one-third of the popular AFK core, Fini's job is to be the bulkiest of the three while dishing out respectably strong special attacks. Muddy Water is chosen as the water stab because of its spread targeting and chance of accuracy drop on hit, both of which make up for the lack of damage output. Moonblast is the fairy stab of choice, Protect is used to scout for an opponent's intentions and buy time on the clock, and Soak is a rather gimmicky move to be sure which is incredibly useful against all manner of threats, taking away their stabs and setting them up to be cut to ribbons by a well-placed Leaf Blade or Thunderbolt from one of its partners. Misty Surge is incredibly useful in shutting down enemy fake outs, so it's a good lead choice in order to make sure the enemy doesn't gain momentum right off the bat. Bold is chosen to boost its otherwise uninvested defense, though it still doesn't want to take a poison jab unless it absolutely has to. Wiki Berry allows it to gain back health and continue doing its job of bulky offense to wear down the foe and set them up for a devastating blow.
Arcanine @ Firium Z
Ability: Intimidate
Level: 50
EVs: 4 HP / 252 Atk / 252 Speed
Jolly Nature
-Flare Blitz
-Wild Charge
-Extreme Speed
-Protect
Attack doggo is an obvious and excellent set. Intimidate support is extremely valuable to undo opposing beast boosts and further shore up the team's general lack of physical defense. While Extremespeed doesn't work in misty terrain, it still has plenty of utility and versatility, especially if Trick Room comes into play. Wild Charge lets it function against opposing Fini, but one should take care if Milotic is present in team preview. Firium Z is chosen in order to let the doggo go out with a bang that goes through protects, especially to hammer hail mode teams and get through Tapu Bulu without the problems of potentially having a Gigavolt Havoc getting redirected and absorbed. A Jolly nature is chosen to help scout the opponent's sets, particularly when it comes to speed investment for things like Togedemaru and Mimikyu that just creep over its speed tier.
Kartana @ Assault Vest
Ability: Beast Boost
Level: 50
EVs: 56 HP / 200 Atk / 252 Speed
Jolly Nature
-Leaf Blade
-Smart Strike
-Detect
-Laser Focus
Kartana's job is simple: Do 9/11 by cutting down towers with one stroke. When it's not committing terrorism, it settles for giving its enemies vicious paper cuts. Leaf Blade and Smart Strike are the obvious choices for stab attacks, Detect is chosen to avoid Imprison problems despite having half the PP, and the unique move Laser Focus guarantees that the next attack will result in a critical hit, which bypasses defense boosts on top of dealing 1.5x damage. The EVs are chosen to give Kartana a little extra breathing room defensively while still letting Beast Boost increase its attack stat. Jolly is chosen in order to outrun Garchomp, though it's still too frail to go without support against things like Celesteela. I was considering Brick Break in the last slot, but the only real screen you see in this format is Aurora Veil and this team has enough ways to deal with Ninetales and Sandslash-A.
Tapu Koko @ Fairium Z
Ability: Electric Surge
Level: 50
EVs: 4 HP / 252 SpAtk / 252 Speed
Modest Nature
-Thunderbolt
-Dazzling Gleam
-Nature Power
-Protect
The second half of the one-two punch that Soak can provide, alongside Kartana's leaf blade. The great part about Nature Power is that it turns into Thunderbolt in electric terrain, so it's a good move to click on if you're worried about a potential switch or if you've lost the terrain war. Nature Power does grant STAB if the move it turns into matches the user's type (in particular, if misty terrain is out, it turns into Moonblast, something Koko does not ordinarily have access to), so it's applicable in a wide variety of situations. Thunderbolt and Dazzling Gleam are run alongside it for the sake of consistency, though if a Muk-Alola or Garchomp really needs to die, it can pop Twinkle Tackle and really put the hurt on without worrying about a Marowak-A coming in to spoil the fun. Due to Koko's frailty, Protect is a needed investment of a moveslot to help it stay safe. The EVs and nature are chosen because although Koko's physical attack stat is superior, most of its good attacks are special, including everything that Nature Power turns into. It struggles against Kartana, though its neutrality to steel attacks makes up for it somewhat.
Porygon2 @ Eviolite
Ability: Download
Level: 50
EVs: 244 HP / 12 Atk / 252 SpAtk
Quiet Nature
-Thunderbolt
-Ice Beam
-Return
-Trick Room
In case of trick room setups, pull PG lever. This defensive behemoth can get download boosts to further enhance its impressive special attack and great boltbeam coverage. Return is chosen as the STAB move in case of Download boosting attack instead (also explaining the mild investment in that stat). The Quiet nature is chosen to ensure P2 hits minimum speed. It's possible that a 0 Speed IV could be run to further make use of this, but it too has issues with Kartana, particularly if it has Assault Vest or Sacred Sword.
Gigalith @ Weakness Policy
Ability: Sand Stream
Level: 50
EVs: 244 HP / 252 Atk / 12 SpDef
Adamant Nature
-Rock Slide
-Heavy Slam
-Wide Guard
-Stone Edge
A sand streamer is needed to offset grassy terrain and leftovers heals from the opposing team. Enter Gigalith, who also takes insane advantage of P2's TR. Heavy Slam is intended as an anti-tapu measure, and Rock Slide is good for causing flinches in TR, so it's a good move in the format despite the lack of damage output (it's barely better than a smack down after the multi-target penalty). Stone Edge is the choice against Celesteela, Arcanine or Marowak-A. Despite its miss chance, its sheer power is unrivaled for rock stab. The EVs are chosen not only so that Gigalith can benefit from his own sand, but also so that he can survive a super effective hit to get the weakness policy going and really start leaving a mark. Adamant nature is chosen to further boost this massive attack stat, enough to offset enemy Arcanine and their attempts to intimidate, or even the rare Parting Shot.
You're just missing the point of explaining your sets: You don't have to tell us that muddy water has chance for accuracy drops, we already know that. Don't explain what the moves do but try to explain why you chose them over other choices. I found a good example how to do it from your post: "Intimidate support is extremely valuable to ... further shore up the team's general lack of physical defense". You're using intimidate over abilities to cover up your team's weakness to physical attack, now that's a good explanation. More of that and you'll definitely pass ;)