This was my third team built for OU. After getting bored with Gholdengo hazard stack, I wanted to try stall. The team got me halfway to reqs for the tera suspect, but it just started struggling into Valiant and Chi-Yu.
Teambuilding
+
+
The original team was based on the trinity of new Unaware mons. Dondozo was a huge physical wall, and I loved the CroDozo set, Clodsire was my special wall and Skeledirge sat in the middle, as a phaser.
+++
I liked the look of Garg early on. Body Press+Iron Defense was the main play, with salt cure. This was long before the protect set.
++++
+
There was a period of messing with the final 2 slots, before I settled on Corviknight and Chi-Yu. Corv was mainly there for the Meowscarada that plagued the format, and to give a ground immunity, while Chi-Yu was brought on as spot removal with tera fire overheat.
+++++
3 Unaware mons on a team sounds awesome, until you realize its a little rough dealing with Gholdengo and Chi-Yu, who nuke from orbit repeatedly with Make It Rain and Overheat respectively. I also had a lot of Iron Valiant issues. To handle both, I switched it out to Scizor, which gave me some much needed priority.
+++++
Garganacl just started to become a little redundant on the team. Dozo and corv provided enough tanking power, and I realized how weak to electric attack I was, so Amoonguss was adopted. Nice regen pivot and provided some cool utilities.
The Team:
Derp (Dondozo) @ Leftovers
Ability: Unaware
Tera Type: Water
EVs: 248 HP / 252 Def / 8 SpD
Impish Nature
- Liquidation
- Curse
- Rest
- Sleep Talk
Dondozo is the ace of the team. It beats virtually any physical attacker with this set. Get to +6/+6 is ideal, then Liquidation everything. Rest is for healing, and I chose sleep talk, so I'm not a dead weight for 2 turns.
Leftovers is the best item here, providing some passive healing, and Full Phys Def for just making people's life a nightmare. Special defense would be a waste on it. I would be lying if I said tera water was intentional, but it's just stayed that way.
Flop (Clodsire) @ Black Sludge
Ability: Unaware
Tera Type: Water
EVs: 248 HP / 8 Def / 252 SpD
Careful Nature
- Earthquake
- Toxic
- Stealth Rock
- Recover
Specially defensive Clodire synergises very well with Dondozo. I chose for it to be my rocker, but does have issues into the paradox Donphans. EQ is for STAB and recover for healing. I chose Toxic to round it out, as it provides ways of punishing Ting-Lu and other bad switches. Tera water was just to complement it's typing, but I do think something else is wanted.
I Hate Tinkaton (Corviknight) @ Leftovers
Ability: Pressure
Tera Type: Dark
EVs: 252 HP / 252 Def / 4 SpD
Relaxed Nature
IVs: 0 Spe
- Body Press
- Roost
- U-turn
- Defog
This corv is probably a little different to the meta. I prefer Body Press over Brave Bird, as it's not really going to stare down Gholdengo. U-turn for pivot, Defog for hazard control and Roost for healing.
I chose phys def Corviknight, as it worked better into Great Tusk and Iron Treads. Leftovers was chosen over Helmet, as it provided better usage into repeated Gholdengo switches (Nearly ended up as HDB at one point). Tera Dark was suggested early on as an answer to priority Taunt from Grimmsnarl, but it's kinda died off. Min speed was chosen, as a slow pivot provides great options into counters trying to take out the bird. Most of the time, Chi-Yu comes in and clicks the delete button.
I'm in Danger (Chi-Yu) @ Choice Specs
Ability: Beads of Ruin
Tera Type: Fire
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Overheat
- Dark Pulse
- Flamethrower
- Psychic
This thing is evil. Mainly picked as an offensive threat to get the jump on Annihilape, Chi-Yu provides a strong answer to tankier mons that try to take advantage of my team's passive nature. Tera fire was chosen to allow this Pokemon insane wall breaking potential, and accompanies the potent Flamethrower and nuclear Overheat. Dark Pulse for second STAB and Psychic to round out the coverage. 90% of the time, I'm clicking a fire move.
Timid Specs was chosen to get the jump on other Chi-Yu, and just break stuff.
The Claw (Scizor) @ Leftovers
Ability: Technician
Tera Type: Steel
EVs: 252 HP / 236 SpD / 20 Spe
Careful Nature
- U-turn
- Bullet Punch
- Swords Dance
- Thief
After too much time losing to Iron Valiant, I added Scizor to the team. I chose a specially defensive build more to take Gholdengo, and allow it to convert into an endgame sweeper with SD. Bullet Punch+Technician is the main reason Scizor was picked, as it snipes Valiants that are still weak to Steel, though an SD is needed for the OHKO. U-Turn game another pivot. As for the final move, Thief was picked to not get walled by Gholdengo, and be threatening. Steel Tera type allows the main STAB Bullet Punch to hit that much harder.
Shroomsday (Amoonguss) @ Rocky Helmet
Ability: Regenerator
Tera Type: Water
EVs: 252 HP / 172 Def / 84 SpD
Bold Nature
IVs: 0 Atk
- Giga Drain
- Sludge Bomb
- Foul Play
- Spore
This was the current temp set from the dex, but it does work. Giga Drain for healing, Sludge bomb for second coverage, and a harder hit into Iron Valiant, while foul play punishes physical setup mons, and allows damage onto . Spore takes out a pokemon Helmet allowed me to punish Physical attackers, while regen allows consistent healing on switch. It's a bog standard mon, but acts as nice glue
How it usually plays:
Most of the time, the team leads Chi-Yu or Corviknight. Chi-Yu lead can put you in a dominant spot, and an early big hit can break a team. However, those with Garchomp, Ting-Lu or Glimmora leads, Corv is usually better. Corv can pivot into Clodsire on Glimmora, breaking sash and absorbing the toxic spikes. An EQ later, and it should be down with minimal losses.
Issues
- A major pain. If it lacks a Psychic coverage move, and is special, it's defensively switched in by Clodsire, and forcing a retreat or Toxic.
- Issue is no real major answer to it if its the dual hazard lead. Dragon Tail hurts too, and the Gholdengo its usually paired with makes dealing with hazards hard. Late game, Dondozo handles it, but it can put effort in hard.
- If I can catch them with the body press on a switch, its fine. If it lacks specs+overheat+tera fire, clodsire can deal with it enough. If I scout the scarf, then I can force an overheat KO.
- Only the specs variant. Cause it can repeatedly Draco into my Clod, I can't continually wear it down. And, Corv takes a lot still. The main answer is Pressure stall and Clodsire walling it. If I can drop a toxic, its peachy.
Hazard Spam - Gholdengo hazard stack teams can really wear the team down. Repeated damage and hard hitting moves. I have floated the idea of HDB corv, to allow switching in, but its a pain. Hopefully Ace's return causes havoc for those team with Court Change
Importable
https://pokepast.es/39987451745fe7c6
Teambuilding
++The original team was based on the trinity of new Unaware mons. Dondozo was a huge physical wall, and I loved the CroDozo set, Clodsire was my special wall and Skeledirge sat in the middle, as a phaser.
+++I liked the look of Garg early on. Body Press+Iron Defense was the main play, with salt cure. This was long before the protect set.
+++++There was a period of messing with the final 2 slots, before I settled on Corviknight and Chi-Yu. Corv was mainly there for the Meowscarada that plagued the format, and to give a ground immunity, while Chi-Yu was brought on as spot removal with tera fire overheat.
+++++3 Unaware mons on a team sounds awesome, until you realize its a little rough dealing with Gholdengo and Chi-Yu, who nuke from orbit repeatedly with Make It Rain and Overheat respectively. I also had a lot of Iron Valiant issues. To handle both, I switched it out to Scizor, which gave me some much needed priority.
+++++Garganacl just started to become a little redundant on the team. Dozo and corv provided enough tanking power, and I realized how weak to electric attack I was, so Amoonguss was adopted. Nice regen pivot and provided some cool utilities.
The Team:
Derp (Dondozo) @ Leftovers
Ability: Unaware
Tera Type: Water
EVs: 248 HP / 252 Def / 8 SpD
Impish Nature
- Liquidation
- Curse
- Rest
- Sleep Talk
Dondozo is the ace of the team. It beats virtually any physical attacker with this set. Get to +6/+6 is ideal, then Liquidation everything. Rest is for healing, and I chose sleep talk, so I'm not a dead weight for 2 turns.
Leftovers is the best item here, providing some passive healing, and Full Phys Def for just making people's life a nightmare. Special defense would be a waste on it. I would be lying if I said tera water was intentional, but it's just stayed that way.
Flop (Clodsire) @ Black Sludge
Ability: Unaware
Tera Type: Water
EVs: 248 HP / 8 Def / 252 SpD
Careful Nature
- Earthquake
- Toxic
- Stealth Rock
- Recover
Specially defensive Clodire synergises very well with Dondozo. I chose for it to be my rocker, but does have issues into the paradox Donphans. EQ is for STAB and recover for healing. I chose Toxic to round it out, as it provides ways of punishing Ting-Lu and other bad switches. Tera water was just to complement it's typing, but I do think something else is wanted.
I Hate Tinkaton (Corviknight) @ Leftovers
Ability: Pressure
Tera Type: Dark
EVs: 252 HP / 252 Def / 4 SpD
Relaxed Nature
IVs: 0 Spe
- Body Press
- Roost
- U-turn
- Defog
This corv is probably a little different to the meta. I prefer Body Press over Brave Bird, as it's not really going to stare down Gholdengo. U-turn for pivot, Defog for hazard control and Roost for healing.
I chose phys def Corviknight, as it worked better into Great Tusk and Iron Treads. Leftovers was chosen over Helmet, as it provided better usage into repeated Gholdengo switches (Nearly ended up as HDB at one point). Tera Dark was suggested early on as an answer to priority Taunt from Grimmsnarl, but it's kinda died off. Min speed was chosen, as a slow pivot provides great options into counters trying to take out the bird. Most of the time, Chi-Yu comes in and clicks the delete button.
I'm in Danger (Chi-Yu) @ Choice Specs
Ability: Beads of Ruin
Tera Type: Fire
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Overheat
- Dark Pulse
- Flamethrower
- Psychic
This thing is evil. Mainly picked as an offensive threat to get the jump on Annihilape, Chi-Yu provides a strong answer to tankier mons that try to take advantage of my team's passive nature. Tera fire was chosen to allow this Pokemon insane wall breaking potential, and accompanies the potent Flamethrower and nuclear Overheat. Dark Pulse for second STAB and Psychic to round out the coverage. 90% of the time, I'm clicking a fire move.
Timid Specs was chosen to get the jump on other Chi-Yu, and just break stuff.
The Claw (Scizor) @ Leftovers
Ability: Technician
Tera Type: Steel
EVs: 252 HP / 236 SpD / 20 Spe
Careful Nature
- U-turn
- Bullet Punch
- Swords Dance
- Thief
After too much time losing to Iron Valiant, I added Scizor to the team. I chose a specially defensive build more to take Gholdengo, and allow it to convert into an endgame sweeper with SD. Bullet Punch+Technician is the main reason Scizor was picked, as it snipes Valiants that are still weak to Steel, though an SD is needed for the OHKO. U-Turn game another pivot. As for the final move, Thief was picked to not get walled by Gholdengo, and be threatening. Steel Tera type allows the main STAB Bullet Punch to hit that much harder.
Shroomsday (Amoonguss) @ Rocky Helmet
Ability: Regenerator
Tera Type: Water
EVs: 252 HP / 172 Def / 84 SpD
Bold Nature
IVs: 0 Atk
- Giga Drain
- Sludge Bomb
- Foul Play
- Spore
This was the current temp set from the dex, but it does work. Giga Drain for healing, Sludge bomb for second coverage, and a harder hit into Iron Valiant, while foul play punishes physical setup mons, and allows damage onto . Spore takes out a pokemon Helmet allowed me to punish Physical attackers, while regen allows consistent healing on switch. It's a bog standard mon, but acts as nice glue
How it usually plays:
Most of the time, the team leads Chi-Yu or Corviknight. Chi-Yu lead can put you in a dominant spot, and an early big hit can break a team. However, those with Garchomp, Ting-Lu or Glimmora leads, Corv is usually better. Corv can pivot into Clodsire on Glimmora, breaking sash and absorbing the toxic spikes. An EQ later, and it should be down with minimal losses.
Issues
- A major pain. If it lacks a Psychic coverage move, and is special, it's defensively switched in by Clodsire, and forcing a retreat or Toxic. - Issue is no real major answer to it if its the dual hazard lead. Dragon Tail hurts too, and the Gholdengo its usually paired with makes dealing with hazards hard. Late game, Dondozo handles it, but it can put effort in hard. - If I can catch them with the body press on a switch, its fine. If it lacks specs+overheat+tera fire, clodsire can deal with it enough. If I scout the scarf, then I can force an overheat KO. - Only the specs variant. Cause it can repeatedly Draco into my Clod, I can't continually wear it down. And, Corv takes a lot still. The main answer is Pressure stall and Clodsire walling it. If I can drop a toxic, its peachy.Hazard Spam - Gholdengo hazard stack teams can really wear the team down. Repeated damage and hard hitting moves. I have floated the idea of HDB corv, to allow switching in, but its a pain. Hopefully Ace's return causes havoc for those team with Court Change
Importable
https://pokepast.es/39987451745fe7c6
the first change i suggest is changing amoonguss to tinglu. 
my second change i recommend is changing scizor to gholdengo. it was mentioned in your post that sd scizor was used to deal with iron valiant, but with tera steel being very popular, it will be hard to pick off a threatening valiant with scizor that will just get 2hkoed. on the other hand,