Project SV OU - Victim of the Week (Week 74: Assault Vest Hoopa-U)

[Jertsi]

Check

Dondozo @ Leftovers
Level: 100
Impish Nature
Tera Type: Fighting
Ability: Unaware
EVs: 252 HP / 252 Def / 4 SpD
- Waterfall
- Sleep Talk
- Rest
- Curse

Tyranitar:
252+ Atk Choice Band Tyranitar Stone Edge vs. 252 HP / 252+ Def Dondozo: 180-213 (35.7 - 42.2%) -- guaranteed 3HKO after sandstorm damage and Leftovers recovery
252+ Atk Choice Band Tyranitar Knock Off (97.5 BP) vs. 252 HP / 252+ Def Dondozo: 175-207 (34.7 - 41%) -- guaranteed 3HKO after sandstorm damage
(No item: 252+ Atk Choice Band Tyranitar Knock Off vs. 252 HP / 252+ Def Dondozo: 118-139 (23.4 - 27.5%) -- 0.9% chance to 3HKO after sandstorm damage)
252+ Atk Choice Band Tyranitar Stone Edge vs. 252 HP / 252+ Def Dondozo: 180-213 (35.7 - 42.2%) -- guaranteed 3HKO after sandstorm damage and Leftovers recovery

After 1 Curse:
252+ Atk Choice Band Tyranitar Stone Edge vs. +1 252 HP / 252+ Def Dondozo: 120-142 (23.8 - 28.1%) -- 92.9% chance to 4HKO after sandstorm damage and Leftovers recovery

Dondozo:
0 Atk Dondozo Waterfall vs. 88 HP / 0 Def Tyranitar: 158-188 (43.5 - 51.7%) -- 9.4% chance to 2HKO
+1 0 Atk Dondozo Waterfall vs. 88 HP / 0 Def Tyranitar: 236-282 (65 - 77.6%) -- guaranteed 2HKO

After one Curse you are free to Rest whenever needed.

Can also be turned into a counter if Tera Fighting is available (not sure if tera is allowed to counter a mon), as it drops Ttars damage drastically:
252+ Atk Choice Band Tyranitar Low Kick (120 BP) vs. 252 HP / 252+ Def Tera Fighting Dondozo: 144-170 (28.5 - 33.7%) -- 0.5% chance to 3HKO after sandstorm damage and Leftovers recovery
252+ Atk Choice Band Tyranitar Stone Edge vs. 252 HP / 252+ Def Tera Fighting Dondozo: 90-106 (17.8 - 21%) -- possible 5HKO

 

[HydreigonTheChild]

Zamazenta @ Leftovers
Ability: Dauntless Shield
EVs: 252 HP / 88 Def / 168 Spe
Tera Type: Fire
Jolly Nature
- Iron Defense
- Body Press
- Crunch
- Roar

Zama-H is a check as it can take it on with resisting both of its stabs, and especially on the first time it switches in. It can even use it for setup fother for ID Press sets. Its lack of longetivity stops it from checking it better

Great Tusk @ Rocky Helmet
Ability: Protosynthesis
EVs: 252 HP / 4 Atk / 252 Spe
Tera Type: Water
Jolly Nature
- Headlong Rush
- Ice Spinner
- Rapid Spin
- Stealth Rock

Defensive tusk is a great stop vs it as anything but ice punch is a 3hko at best while you can rack up helmet damage, headlong rush for a knockout after a round of rocks, or setup rocks and spin to get ur team out of trouble

 

[kd458]

Extending this until Wednesday 19th November as we currently have no counters; any posted now will win by default, unless more than one are submitted!

Iron Hands

Iron Hands @ Booster Energy / Shuca Berry
Ability: Quark Drive
EVs: 252 Atk / 172 SpD / 84 Spe
Tera Type: Flying
Adamant Nature
- Swords Dance
- Drain Punch
- Thunder Punch
- Ice Punch

Also, I will say that this Iron Hands set is not actually a safe check to CB Tyranitar. Choice Band Low Kick has a roll to 2HKO Iron Hands especially when boosted by a turn of Sandstorm chip, while Drain Punch (if Tyranitar uses Tera Flying) does not heal enough back to save Hands from a roll to go down before it can even take Tyranitar out on the next turn.

252+ Atk Choice Band Tera Flying Tyranitar Low Kick (120 BP) vs. 0 HP / 0 Def Iron Hands: 206-243 (45.8 - 54.1%) -- guaranteed 2HKO after sandstorm damage

I'm willing to accept this Hands set as a check if you modify it, the current EVs in SpDef and Speed are unnecessary as is the Shuca Berry as this Tyranitar set does not even pack Earthquake. Just be sure to confirm in the calc whether your check can safely take on the listed threat beforehand!

 

[kd458]

Don't want to drag this on for too long, thank you all for the submissions this week! I'm also going to accept Dondozo as a counter, using Tera is fine here, so congrats on the win!

Great Tusk

I cannot accept this as a counter, as this set is cleanly 3HKOed by Tyranitar's Low Kick. Tera Flying Tyranitar does get barely 2HKOed by Ice Spinner + Rocky Helmet chip, but you have to play a mindgame every turn between Headlong Rush and Ice Spinner until Tyranitar uses Tera. Even just clicking Headlong Rush once as Tyranitar uses Tera Flying would make it win the matchup, while you cannot afford to click Ice Spinner predicting the Tera if they choose not to use it.

252+ Atk Choice Band Tera Flying Tyranitar Low Kick (120 BP) vs. 252 HP / 0 Def Great Tusk: 175-206 (40.3 - 47.4%) -- guaranteed 3HKO
4 Atk Great Tusk Ice Spinner vs. 88 HP / 0 Def Tera Flying Tyranitar: 136-160 (37.4 - 44%) -- 0.4% chance to 2HKO after sandstorm damage
4 Atk Great Tusk Ice Spinner vs. 88 HP / 0 Def Tyranitar: 68-80 (18.7 - 22%) -- possible 5HKO

This is a check, but keep in mind that you're only allowed to submit one check per week and I've already accepted Zamazenta! Also, please don't just pull sets from the Damage Calc unless they're very clearly a good enough answer; there is no reason for this Tusk to be Tera Water or have any speed investment against CB Tyranitar, let alone max speed Jolly, and an alternative spread and Tera Type would make this into a counter.

Checks

Bulk Up by InvisibleWater
by Lectrys
by HydreigonTheChild

Counter

Tera Fighting by Jertsi

Voting will end on Wednesday 26th November 11:59pm EST.
You may vote for 1 check this week!​

 

[InvisibleWater]

Check:

 

[Lectrys]

Check:

 

[kd458]

Congrats on our winner this week!

Check

by HydreigonTheChild
​

No new week right away though, as my cohost is stepping down. Instead, I'd like to reach out and ask here whether anyone here would be interested in hosting VotW? You would still be allowed to post your own submissions for checks & counters every week, but you'd also be able to come up with threats and post them every other week, alternating with your cohost. If anyone with long-term activity here would like to host this project then that would be fantastic, but if not I can also look for hosting elsewhere so don't worry, we will be back no matter what!

Let me know if you're interested!

 

[Avira]

JP and I will be the new co-hosts of this project since kd458 is handing over the reins to us, and we thank her for running this for so long.

This week, I'll be showcasing a Gholdengo set that has been brought to tours by oldspicemike and also by sky. oldspicemike has used Focus Blast in the past, and sky, during OUPL Week 6, used Make It Rain in place of Focus Blast.

Gholdengo @ Grassy Seed
Ability: Good As Gold
EVs: 252 HP / 196 SpD / 60 Spe
Tera Type: Water
Calm Nature
- Focus Blast/Make it Rain
- Nasty Plot
- Recover
- Shadow Ball

With a Grassy Seed boost, it can be hard to break Gholdengo with physical attackers outside of Choice Band users, select threats that can hit Gholdengo for SE damage, or Tera-boosted attacks. For the purpose of this project, Grassy Terrain is assumed to be on the field already, so Gholdengo will have gotten its boost. Tera Water allows for Gholdengo use Great Tusk as set-up fodder and to safely nail Kingambit with Focus Blast since it sheds its Ground and Dark weaknesses. This set is a big threat to teams without multiple strong special attackers as it uses Ting-Lu for set-up fodder, which a lot of players use to get chip on Gholdengo, and many typical checks to it lose the 1v1. Shadow Ball and Focus Blast make for excellent neutral coverage into nearly everything that exists this generation while using Make It Rain in place of Focus Blast is suitable for Focus Blast's issues of consistency due to its miss chance and for a better match-up into Primarina. Are there any Pokemon that can comfortably handle this set?


Submissions are open until Friday, December 20th at 11:59PM EST
You may submit up to 1 check and 1 counter!

 

[Hittite Jumpscare]

Check:

Hoopa-Unbound @ Choice Specs
Ability: Magician
Tera Type: Fighting
EVs: 128 HP / 4 Def / 252 SpA / 124 Spe
Modest Nature
IVs: 0 Atk
- Dark Pulse
- Thunderbolt
- Focus Blast
- Psyshock

Specs Dark Pulse 2HKOs even if Dengo teras and GTerrain is up. The given EVs allow Hoopa to survive a +2 Make It Rain and still outspeed Dengo. 124 speed allows Hoopa to outrun regular Gliscors.

252+ SpA Choice Specs Hoopa-Unbound Dark Pulse vs. 252 HP / 196+ SpD Tera Water Gholdengo: 211-250 (55.8 - 66.1%) -- guaranteed 2HKO after Grassy Terrain recovery
+2 0 SpA Tera Water Gholdengo Make It Rain vs. 128 HP / 0 SpD Hoopa-Unbound: 262-310 (78.6 - 93%) -- guaranteed 2HKO after Grassy Terrain recovery

Counter:

Alomomola @ Assault Vest
Ability: Regenerator
Tera Type: Fairy
EVs: 24 HP / 232 Def / 252 SpD
Sassy Nature
IVs: 0 Spe
- Flip Turn
- Scald
- Mirror Coat
- Body Slam

Somehow Alo survives a +6 Shadow Ball. Thus it can just spam Mirror Coat until the Dengo chokes. Meanwhile it can also inflict status with Body Slam or Scald, limiting Dengo's potential overall.

+6 0 SpA Gholdengo Shadow Ball vs. 24 HP / 252+ SpD Assault Vest Alomomola: 334-394 (70 - 82.5%) -- guaranteed 2HKO after Grassy Terrain recovery

 

[Lectrys]

Check


Ogerpon-Wellspring (F) @ Wellspring Mask
Ability: Water Absorb
Tera Type: Water
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Swords Dance
- Ivy Cudgel
- Power Whip
- Play Rough

The opposing Gholdengo needs to not have a Nasty Plot up before Ogerpon-W gets in, but Ogerpon-W can Swords Dance into 2HKO.


0 SpA Gholdengo Shadow Ball vs. 0 HP / 4 SpD Ogerpon-Wellspring: 114-135 (37.8 - 44.8%) -- guaranteed 3HKO after Grassy Terrain recovery
+2 0 SpA Gholdengo Shadow Ball vs. 0 HP / 4 SpD Ogerpon-Wellspring: 228-268 (75.7 - 89%) -- guaranteed 2HKO after Grassy Terrain recovery


+2 252 Atk Wellspring Mask Ogerpon-Wellspring Ivy Cudgel vs. +1 252 HP / 0 Def Gholdengo: 258-304 (68.2 - 80.4%) -- guaranteed 2HKO after Grassy Terrain recovery
+2 252 Atk Wellspring Mask Ogerpon-Wellspring Ivy Cudgel vs. +1 252 HP / 0 Def Tera Water Gholdengo: 129-152 (34.1 - 40.2%) -- 39.9% chance to 3HKO after Grassy Terrain recovery
+2 252 Atk Wellspring Mask Ogerpon-Wellspring Power Whip vs. +1 252 HP / 0 Def Gholdengo in Grassy Terrain: 201-237 (53.1 - 62.6%) -- guaranteed 2HKO after Grassy Terrain recovery
+2 252 Atk Wellspring Mask Ogerpon-Wellspring Power Whip vs. +1 252 HP / 0 Def Tera Water Gholdengo in Grassy Terrain: 804-948 (212.6 - 250.7%) -- guaranteed OHKO

 

[InvisibleWater]

Clodsire @ Heavy-Duty Boots
Ability: Unaware
EVs: 248 HP / 8 Def / 252 SpD
Tera Type: Steel
Careful Nature
- Earthquake
- Recover
- Poison Jab
- Amnesia

Clodsire is a counter. Unaware and Amnesia boosts keep Gholdengo from making any sort of progress. Make it Rain is, at most, a 4HKO under Grassy Terrain, which can be reduced even further via Tera Steel, and if it's running Focus Blast Clodsire doesn't even need to do that.

Of course, since Gholdengo also benefits from Grassy Terrain and has Recover, Clodsire won't be doing much in return either. Tera Water does make it vulnerable to Poison Jab procs, but outside of that, there's not much Clodsire can do besides force it to switch out and waste its Grassy Seed.

Calcs

0 Atk Unaware Clodsire Earthquake vs. 252 HP / 196+ Def Gholdengo in Grassy Terrain: 66-80 (17.4 - 21.1%) -- possible 7HKO
0 Atk Clodsire Earthquake vs. 252 HP / 196+ Def Gholdengo: 134-158 (35.4 - 41.7%) -- guaranteed 3HKO
0 Atk Unaware Clodsire Earthquake vs. 252 HP / 196+ Def Tera Water Gholdengo in Grassy Terrain: 33-40 (8.7 - 10.5%) -- possibly the worst move ever
0 Atk Clodsire Earthquake vs. 252 HP / 196+ Def Tera Water Gholdengo: 67-79 (17.7 - 20.8%) -- possible 5HKO
0 Atk Unaware Clodsire Poison Jab vs. 252 HP / 196+ Def Tera Water Gholdengo: 54-64 (14.2 - 16.9%) -- possible 9HKO


0 SpA Gholdengo Shadow Ball vs. 248 HP / 252+ SpD Clodsire: 79-94 (17 - 20.3%) -- possible 7HKO
0 SpA Gholdengo Shadow Ball vs. +2 248 HP / 252+ SpD Clodsire: 40-48 (8.6 - 10.3%) -- possibly the worst move ever
0 SpA Gholdengo Focus Blast vs. 248 HP / 252+ SpD Clodsire: 39-47 (8.4 - 10.1%) -- possibly the worst move ever
0 SpA Gholdengo Focus Blast vs. +2 248 HP / 252+ SpD Clodsire: 20-24 (4.3 - 5.1%) -- possibly the worst move ever
0 SpA Gholdengo Make It Rain vs. 248 HP / 252+ SpD Clodsire: 118-141 (25.4 - 30.4%) -- 1.9% chance to 4HKO after Grassy Terrain recovery
0 SpA Gholdengo Make It Rain vs. +2 248 HP / 252+ SpD Clodsire: 60-72 (12.9 - 15.5%) -- possibly the worst move ever

 

[kd458]

Check

Moltres-Galar @ Heavy-Duty Boots
Ability: Berserk
Tera Type: Fairy
EVs: 24 HP / 252 SpA / 232 Spe
Modest Nature
IVs: 0 Atk
- Fiery Wrath
- Tera Blast
- Agility
- Nasty Plot
​

Moltres-Galar has enough base SpDef to comfortably 1v1 Gholdengo from an even game state, with its unique typing allowing it to resist Shadow Ball without being weak to Make it Rain. The Tera Type and even item choice here don't matter at all, with Boots chosen as an option to make this a check even if rocks are up. The selected EV spread allows it to outspeed Iron Valiant after an Agility whilst giving it a tiny bit of bulk, enough to survive Gholdengo's +2 Make it Rain.

Offensive calcs

There is no reason for Gholdengo to not Tera, so Moltres-G should always go for a Nasty Plot first. After a Plot, Moltres-G can just click Fiery Wrath until Gholdengo goes down!
+2 252+ SpA Moltres-Galar Fiery Wrath vs. 252 HP / 196+ SpD Tera Water Gholdengo: 217-256 (57.4 - 67.7%) -- guaranteed 2HKO after Grassy Terrain recovery

What can Gholdengo do back?

As the offensive calcs show, Gholdengo only has two turns to get damage in before Nasty Plot -> Fiery Wrath -> Fiery Wrath takes it down. Its best line of action is therefore clicking Nasty Plot into Make it Rain itself, but with a few EVs invested in HP, Moltres-G is able to survive this.
+2 0 SpA Gholdengo Make It Rain vs. 24 HP / 0 SpD Moltres-Galar: 271-321 (82.8 - 98.1%) -- guaranteed 2HKO

Any other move bounces off, so attacking twice is always worse!
0 SpA Gholdengo Shadow Ball vs. 24 HP / 0 SpD Moltres-Galar: 45-54 (13.7 - 16.5%) -- possible 7HKO
0 SpA Gholdengo Focus Blast vs. 24 HP / 0 SpD Moltres-Galar: 91-108 (27.8 - 33%) -- guaranteed 4HKO
0 SpA Gholdengo Make It Rain over 2 turns vs. 24 HP / 0 SpD Moltres-Galar: 227-270 (69.4 - 82.5%) -- not a KO

It can easily be shown that Nasty Plot Moltres-Galar is able to safely check even a SpDef-invested Gholdengo set!

Counter

Ursaluna @ Assault Vest
Ability: Bulletproof
Tera Type: Electric
EVs: 80 HP / 176 Atk / 252 SpD
Adamant Nature
- Body Slam
- Headlong Rush
- Supercell Slam
- Ice Punch
​

This does need Tera Electric to comfortably beat Gholdengo, but it can switch in on any move due to Bulletproof and its Assault Vest. This EV spread is guaranteed to 2HKO Gholdengo with Headlong Rush into Supercell Slam, even after Grassy Terrain recovery and regardless of if it chooses to use Tera or not! The Tera Type not only resists Make it Rain but also boosts Supercell Slam, which is actually required as this set does not cleanly 2HKO Tera Water Gholdengo through the Grassy Seed boost without using its own Tera.

Offensive calcs

If Gholdengo chooses not to Tera...
176+ Atk Ursaluna Headlong Rush vs. +1 252 HP / 0 Def Gholdengo: 302-356 (79.8 - 94.1%) -- guaranteed 2HKO after Grassy Terrain recovery
If Gholdengo chooses to Tera...
176+ Atk Ursaluna Headlong Rush vs. +1 252 HP / 0 Def Tera Water Gholdengo: 151-178 (39.9 - 47%) -- guaranteed 3HKO after Grassy Terrain recovery
176+ Atk Tera Electric Ursaluna Supercell Slam vs. +1 252 HP / 0 Def Tera Water Gholdengo: 254-300 (67.1 - 79.3%) -- guaranteed 2HKO after Grassy Terrain recovery

Ursaluna only has to click Headlong Rush twice, as if Gholdengo uses Tera and clicks Recover on either turn it will always still fall to the follow-up Supercell Slam(s)!

What can Gholdengo do back?

This is the maximum Ursaluna can take while switching in, and if Gholdengo clicks Make it Rain here, the SpAtk drop makes this an easy 1v1!
0 SpA Gholdengo Make It Rain vs. 80 HP / 252 SpD Assault Vest Ursaluna: 102-120 (24.2 - 28.5%) -- possible 5HKO

If Gholdengo clicks Nasty Plot as Ursaluna switches in, then attacks with two Make it Rains...
+2 0 SpA Gholdengo Make It Rain vs. 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 100-118 (23.7 - 28%) -- possible 5HKO
+1 0 SpA Gholdengo Make It Rain vs. -1 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 113-133 (26.8 - 31.5%) -- 27.9% chance to 4HKO after Grassy Terrain recovery

If Gholdengo clicks Nasty Plot twice then attacks after the Headlong Rush SpDef drop...
+4 0 SpA Gholdengo Make It Rain vs. -1 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 225-266 (53.4 - 63.1%) -- guaranteed 2HKO after Grassy Terrain recovery

Gholdengo can use Tera and Recover on the first Headlong Rush. This does not change anything if it Nasty Plots again as Ursaluna is then using Supercell Slam x2, but it does matter Ghold clicks Nasty Plot on the switch, Tera + Recover, then Make it Rain twice...
+2 0 SpA Gholdengo Make It Rain vs. -1 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 150-177 (35.6 - 42%) -- 89.3% chance to 3HKO after Grassy Terrain recovery
+1 0 SpA Gholdengo Make It Rain vs. -1 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 113-133 (26.8 - 31.5%) -- 27.9% chance to 4HKO after Grassy Terrain recovery

Gholdengo can also Tera and Recover on the second Headlong Rush. If it clicked Nasty Plot twice, this lets it rip a single +4 MiR into -2 Ursaluna, while if it click MiR on the first turn, it then gets a follow-up +1 MiR into -2 Ursaluna, neither being enough to take it down.
+4 0 SpA Tera Water Gholdengo Make It Rain vs. -2 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 302-356 (71.7 - 84.5%) -- guaranteed 2HKO after Grassy Terrain recovery
or
+2 0 SpA Gholdengo Make It Rain vs. 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 100-118 (23.7 - 28%) -- possible 5HKO
+1 0 SpA Tera Water Gholdengo Make It Rain vs. -2 80 HP / 252 SpD Assault Vest Tera Electric Ursaluna: 151-178 (35.8 - 42.2%) -- 92.4% chance to 3HKO after Grassy Terrain recovery

There is no possible combination of moves where Gholdengo can actually take down this Ursaluna set before being taken down itself!

As can be seen, there is no possible way for Grassy Seed Gholdengo to prevent Tera Electric, Assault Vest & Bulletproof Ursaluna from switching in freely to counter it!

 

[Avira]

Voting is up. I meant to get this up last night, but since I was late, I'll let this run until 11:59 PM EST on December 21.

 

[InvisibleWater]

Check:
Counter:

 

[Hittite Jumpscare]

Check:
Counter:

 

[Lectrys]

Check:
Counter:

 

[kd458]

Check:
Counter:

 

[Hittite Jumpscare]

[redacted]

What's this for?

 

[JP]

Congratulations to our winners this week. Their sets are being added to the hall of fame.

Check

by Hittite Jumpscare

drawn with

by kd458

Counter

by InvisibleWater
​

This week’s victim will be one that has been overlooked for a long time and was even dropped to UU at one point. Recently, however, it has experienced a renaissance with the exploration of new sets. I’m talking about Rillaboom, and one of these sets is:

Rillaboom @ Life Orb
Ability: Grassy Surge
Tera Type: Dark
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Swords Dance
- Grassy Glide
- Knock Off
- Stomping Tantrum​

Life Orb Rillaboom has been growing in popularity recently, as it combines multiple desirable qualities. It packs very strong priority, which is a massive deal this generation because it helps keep powerful offensive threats in check. It also offers immense breaking power, being able to overpower many would-be checks with Swords Dance and Tera Dark Knock Off. Stomping Tantrum is run to hit Weezing-Galar and Kingambit harder and rounds out the coverage nicely. Tera Fairy with Tera Blast has also been seeing a bit of play, even getting a sample, but for now, focusing on this set should be more than enough. Are you able to handle this offensive powerhouse?

Submissions are open until Friday, December 26th at 11:59PM EST
You may submit up to 1 check and 1 counter!

 

[JP]

What's this for?

I messed up the post and posted it accidentally, before deleting it. So they got a little preview. I hope my mistake can be forgiven and no ideas were taken away unfairly

 

[Hittite Jumpscare]

I messed up the post and posted it accidentally, before deleting it. So they got a little preview. I hope my mistake can be forgiven and no ideas were taken away unfairly

Thanks for clearing things up. Deleted your original post so hopefully no one steals your idea.

 

[Hittite Jumpscare]

Check:

Iron Moth @ Choice Specs
Ability: Quark Drive
Tera Type: Fire
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Sludge Wave
- Fiery Dance
- Overheat
- U-turn

Specs Overheat goes brrr.

Calcs!

+2 252+ Atk Life Orb Rillaboom Grassy Glide vs. 0 HP / 4 Def Iron Moth in Grassy Terrain: 122-144 (40.5 - 47.8%) -- guaranteed 3HKO after Grassy Terrain recovery
252 SpA Choice Specs Iron Moth Overheat vs. 0 HP / 0 SpD Tera Dark Rillaboom: 450-531 (131.9 - 155.7%) -- guaranteed OHKO

Counter:

Mandibuzz (F) @ Heavy-Duty Boots
Ability: Overcoat
Tera Type: Water
EVs: 248 HP / 244 Def / 16 Spe
Bold Nature
IVs: 0 Atk
- Foul Play
- Iron Defense
- Roost
- Toxic

Mandibuzz resists all moves, and can stall with Toxic + Iron Defense + Roost. Alternatively, 3 +2 Tera Dark Knock Offs only have a 0.2% chance to KO Mandi, so even if we don't roost for whatever reason, Foul Play most likely wins.

Calcs!

+2 252+ Atk Life Orb Tera Dark Rillaboom Knock Off (97.5 BP) over 3 turns vs. 248 HP / 244+ Def Mandibuzz: 361-426 (85.3 - 100.7%) -- 0.2% chance to 3HKO
+2 252+ Atk Life Orb Rillaboom Grassy Glide vs. 248 HP / 244+ Def Mandibuzz in Grassy Terrain: 114-135 (26.9 - 31.9%) -- guaranteed 4HKO
+2 252+ Atk Life Orb Rillaboom Grassy Glide vs. +2 248 HP / 244+ Def Mandibuzz in Grassy Terrain: 57-68 (13.4 - 16%) -- possible 7HKO
+2 252+ Atk Mandibuzz Foul Play vs. 0 HP / 4 Def Tera Dark Rillaboom: 180-212 (52.7 - 62.1%) -- 99.6% chance to 2HKO after Grassy Terrain recovery
+2 252+ Atk Mandibuzz Foul Play vs. 0 HP / 4 Def Rillaboom: 360-424 (105.5 - 124.3%) -- guaranteed OHKO

 

[Lectrys]

Check


Walking Wake @ Choice Specs
Ability: Protosynthesis
Tera Type: Water
EVs: 12 HP / 244 SpA / 252 Spe
Timid Nature
- Hydro Steam
- Draco Meteor
- Flamethrower
- Dragon Pulse

Rillaboom needs to not have a Swords Dance up, but Walking Wake can tank an unboosted Grassy Glide and OHKO.


252+ Atk Life Orb Rillaboom Grassy Glide vs. 12 HP / 0 Def Walking Wake in Grassy Terrain: 177-211 (51.7 - 61.6%) -- 95.7% chance to 2HKO after Grassy Terrain recovery


244 SpA Choice Specs Walking Wake Draco Meteor vs. 0 HP / 0 SpD Rillaboom: 412-486 (120.8 - 142.5%) -- guaranteed OHKO

 

[InvisibleWater]

Chesnaught @ Rocky Helmet
Ability: Bulletproof
EVs: 252 HP / 252 Def / 4 SpD
Tera Type: Steel
Impish Nature
- Body Press
- Knock Off
- Synthesis
- Iron Defense

Chesnaught is a counter. It takes very little damage from Rillaboom's attacks -- it needs to get to +6 to even 2HKO, and with Iron Defense, even that isn't guaranteed if Chesnaught switches in early enough. In return, Chesnaught can remove Rillaboom's Life Orb with Knock Off or use Body Press, which can KO at +2 after Rocky Helmet chip. If Rillaboom Terastallizes, then it doesn't even need the boosts to do that.

Calcs

252+ Def Chesnaught Body Press vs. 0 HP / 4 Def Rillaboom: 150-177 (43.9 - 51.9%) -- guaranteed 3HKO after Grassy Terrain recovery
+2 252+ Def Chesnaught Body Press vs. 0 HP / 4 Def Rillaboom: 298-352 (87.3 - 103.2%) -- 18.8% chance to OHKO
252+ Def Chesnaught Body Press vs. 0 HP / 4 Def Tera Dark Rillaboom: 300-354 (87.9 - 103.8%) -- 25% chance to OHKO
+2 252+ Def Chesnaught Body Press vs. 0 HP / 4 Def Tera Dark Rillaboom: 596-704 (174.7 - 206.4%) -- guaranteed OHKO
0 Atk Chesnaught Knock Off (97.5 BP) vs. 0 HP / 4 Def Rillaboom: 80-95 (23.4 - 27.8%) -- possible 5HKO
0 Atk Chesnaught Knock Off (97.5 BP) vs. 0 HP / 4 Def Tera Dark Rillaboom: 40-47 (11.7 - 13.7%) -- possibly the worst move ever


252+ Atk Life Orb Rillaboom Grassy Glide vs. 252 HP / 252+ Def Chesnaught in Grassy Terrain: 51-61 (13.4 - 16%) -- possibly the worst move ever
+2 252+ Atk Life Orb Rillaboom Grassy Glide vs. 252 HP / 252+ Def Chesnaught in Grassy Terrain: 101-121 (26.5 - 31.8%) -- 33.7% chance to 4HKO after Grassy Terrain recovery
252+ Atk Life Orb Rillaboom Knock Off (97.5 BP) vs. 252 HP / 252+ Def Chesnaught: 45-55 (11.8 - 14.4%) -- possibly the worst move ever
+2 252+ Atk Life Orb Rillaboom Knock Off (97.5 BP) vs. 252 HP / 252+ Def Chesnaught: 91-108 (23.9 - 28.4%) -- possible 5HKO
252+ Atk Life Orb Tera Dark Rillaboom Knock Off (97.5 BP) vs. 252 HP / 252+ Def Chesnaught: 69-82 (18.1 - 21.5%) -- possible 7HKO
+2 252+ Atk Life Orb Tera Dark Rillaboom Knock Off (97.5 BP) vs. 252 HP / 252+ Def Chesnaught: 136-162 (35.7 - 42.6%) -- 95.5% chance to 3HKO after Grassy Terrain recovery
252+ Atk Life Orb Rillaboom Stomping Tantrum vs. 252 HP / 252+ Def Chesnaught: 36-43 (9.4 - 11.3%) -- possibly the worst move ever
+2 252+ Atk Life Orb Rillaboom Stomping Tantrum vs. 252 HP / 252+ Def Chesnaught: 71-84 (18.6 - 22.1%) -- possible 6HKO

 

[Avira]

I know I'm technically late, but I'm here to also submit a check and a counter.

Check

Zamazenta @ Leftovers
Ability: Dauntless Shield
EVs: 100 HP / 240 Def / 168 Spe
Tera Type: Fire
Jolly Nature
- Iron Defense
- Body Press
- Crunch
- Heavy Slam

This Zama set 1v1s said Rillaboom set assuming no crits since it 2HKOes with a +1 Body Press while a +2 Grassy Glide doesn't 2HKO Zama. I'm not going to call it a counter since the Dauntless Shield boost is for one-turn only, and if you force Rilla out once, and you are in turn forced out, you don't win the next time you come in.

+1 240 Def Zamazenta Body Press vs. 0 HP / 4 Def Rillaboom: 195-229 (57.1 - 67.1%) -- guaranteed 2HKO after Grassy Terrain recovery

Counter

Slither Wing @ Heavy-Duty Boots
Ability: Protosynthesis
EVs: 252 HP / 28 Att / 220 Def
Tera Type : Steel
- Body Press
- First Impression
- Morning Sun
- U-Turn

This Slither Wing set isn't 2HKOed by any of Rillaboom's attacks at +2 and can immediately threaten huge damage with First Impression. First Impression into Body Press always KOes Rillaboom. I have Body Press here instead of Will-O-Wisp as without it Heatran switches in for free and Tera Fire mons set up on you for free. Body Press is also better into Garganacl and lets you have a high chance of OHKOing Kingambit.

28 Atk Slither Wing First Impression vs. 0 HP / 4 Def Tera Dark Rillaboom: 282-332 (82.6 - 97.3%) -- guaranteed 2HKO after Grassy Terrain recovery
220+ Def Slither Wing Body Press vs. 0 HP / 4 Def Kingambit: 340-408 (99.7 - 119.6%) -- 93.8% chance to OHKO