This is a good Trick Room team with a balance of setters and abusers, but the problem is very few of these Pokemon are viable in OU.
Slowking -> Cresselia
Slowking is a pretty good special pivot in OU, but lacks some things that Cresselia has for this team. Namely, Cresselia has better mixed defenses and learns Lunar Dance to support its teammates, making it better overall for a Trick Room team.
Cresselia (F) @ Leftovers
Ability: Levitate
EVs: 252 HP / 4 SpA / 252 SpD
Sassy Nature
IVs: 0 Atk / 0 Spe
- Trick Room
- Moonlight
- Moonblast
- Lunar Dance
Trick Room is Trick Room, Moonlight for recovery, Lunar Dance to heal teammates, and Moonblast has pretty good neutral coverage while still hitting the likes of Urshifu and Weavile. Psyshock or Psychic can be used in place of it, but Moonblast is often more useful. Leftovers is useful for passive recovery.
Golurk -> Alolan Marowak
Golurk is a decent offensive Ghost type, but Alolan Marowak is generally better in a Trick Room team. Due to Thick Club, Marowak essentially gets a free swords dance, as well as great moves like Flare Blitz and Poltergeist which are further bolstered by it's ability, Rock Head.
Marowak-Alola @ Thick Club
Ability: Rock Head
EVs: 252 HP / 252 Atk / 4 SpD
Brave Nature
IVs: 0 Spe
- Swords Dance
- Flare Blitz
- Poltergeist
- Earthquake
Thick Club for the attack boost and Swords Dance can be used to take it even higher. Rock Head is great with Flare Blitz, and Poltergeist is strong STAB. Earthquake is great for hitting the likes of Toxapex and Heatran, but Bonemerang can be used here to break sashes and substitute. However, it has worse accuracy than Earthquake.
Musharna -> Hatterene
Musharna is a powerful special attacker under Trick Room, but has no place in OU. Instead, you should use a suicide lead to set up Trick Room get some momentum going. Uxie is an option, being able to set up Stealth Rock. Hatterene is mostly better due to it's great ability Magic Bounce, which prevents it from being taunted or set up on, making it more useful in most scenarios.
Hatterene (F) @ Focus Sash
Ability: Magic Bounce
EVs: 252 HP / 252 SpA / 4 SpD
Quiet Nature
IVs: 0 Atk / 0 Spe
- Trick Room
- Psyshock
- Mystical Fire
- Misty Explosion
Focus Sash almost guarantees living to set up Trick Room, while Mystical Fire and Psyshock can do some damage before you die. Most of the time, you should just use Misty Explosion after Trick Room to maximize time for your sweepers. You can run a Relaxed nature to guarantee living banded Urshifu's Surging Strikes, but Urshifu isn't often a lead.
Aggron -> Melmetal
Melmetal is a much better Steel-type physical attacker than Aggron, with incredible bulk and power as well as Double Iron Bash. Again, Aggron is not a Pokemon that should be used in OU.
Melmetal @ Choice Band
Ability: Iron Fist
EVs: 252 HP / 252 Atk / 4 SpD
Brave Nature
IVs: 0 Spe
- Double Iron Bash
- Earthquake
- Superpower
- Thunder Punch
As I have said many times, Banded Melmetal is a force to be reckoned with. STAB Double Iron Bash coming off a banded 143 base attack rips through most teams lacking a defensive resist. Ferrothorn and Toxapex put a stop to just spamming Double Iron Bash but they're taken care of with Superpower and Earthquake respectively. Lastly, Thunder Punch is for Flying types that resist Double Iron Bash like Corviknight.
Guzzlord -> Crawdaunt
Again, Guzzlord isn't viable in OU and Crawdaunt is a much better offensive Dark type for Trick Room teams. It has useful priority with Aqua Jet and a great ability in Adaptability.
Crawdaunt @ Life Orb
Ability: Adaptability
EVs: 252 HP / 252 Atk / 4 SpD
Brave Nature
IVs: 0 Spe
- Swords Dance
- Aqua Jet
- Knock Off
- Crabhammer
Swords Dance can be used on a predicted switch, Aqua Jet can finish off low health enemies outside of Trick Room, and Knock Off and Crabhammer are great STABs.
Here's a Pokepaste for the updated team. I also changed the Porygon2 set to be defensive and use Teleport over Substitute for pivoting and Ice Beam over Tri Attack for Landorus.
