Time to share some niche OU sets that I've been having quite a bit of fun with as of late; some of these are tech'd to deal with specific powerful meta threats while some are more generalized against multiple playstyles and fit general team compositions as a whole.
Priority Utility Phaser Flygon

Flygon @ Assault Vest
Ability: Levitate
Tera Type: Bug
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- First Impression
- U-turn
- Earthquake
- Dragon Tail
Flygon has been my favorite anti-meta pick for a little bit now as it has some unique tools that no other Pokemon has access to in the same way - Priority First Impression smacks fast and powerful threats like Darkrai, Deoxys-S, Greninja, Hydrapple, Iron Boulder, Latias, Latios, Necrozma, Ogerpon-Cornerstone, Ogerpon-Wellspring, Rillaboom, Roaring Moon, Samurott-Hisui, Serperior, and Ting-Lu for super effective damage and can be extremely useful against Choice Scarf or just generally faster threats. U-Turn is great for maintaining momentum, while STAB Earthquake can punish multiple common OU threats. STAB Dragon Tail is additionally great for phasing - the combination of phasing + momentum along with priority is something that only Flygon can accomplish. Most of the attacks coming Flygon's way will be special (
as the bulk of physical attacks Flygon resists quite handily), and Levitate further compliments that defensive profile. Tera Bug is useful for two reasons - giving priority First Impression and U-Turn STAB, and granting Flygon a new defensive resistance to Fighting-type attacks (
and turning its 4x Ice weakness into a neutrality). Other Tera-type options are there, of course, but I prefer Tera Bug's offensive utility here personally.
Momentum Blocking Utility Phaser Magmortar

Magmortar @ Heavy-Duty Boots
Ability: Flame Body
Tera Type: Flying
EVs: 248 HP / 8 Atk / 252 Spe
Hasty Nature
- Knock Off
- Roar
- Clear Smog
- Lava Plume
Magmortar got newfound access to both Knock Off and Roar, making it a wonderful offensive utility phaser. You can cripple entire team core setups with this set - Knock Off cripples individual threats while Roar phases problematic Pokemon away. Clear Smog is a Taunt-proof way of stopping setup sweepers while also chipping them for acceptable damage. STAB Lava Plume has a nice burn chance and rounds out this set decently. Magmortar's acceptable special bulk with HP investment allows it to live some surprisingly strong attacks.
Agility Adaptability Tera Sweeper Porygon-Z

Porygon-Z @ Expert Belt
Ability: Adaptability
Shiny: Yes
Tera Type: Fighting
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Tera Blast
- Shadow Ball
- Ice Beam
- Agility
Porygon-Z was born for Tera - Tera Blast is always Adaptability STAB, regardless of your chosen Tera type or whether you even terastallize it that match. I like to go with a Tera Fighting variant as the complimenting coverage of Shadow Ball and Ice Beam works quite well for it. Agility is going to be your primary boosting move, as Porygon-Z's biggest weak point as an offensive sweeper is its lackluster base 90 speed. You can leverage Porygon-Z's nuclear power with Adaptability far better with a +2 speed boost and additionally (mostly) solve Porygon-Z's long-existing issues with 4MSS thanks to Tera plus the additional Adaptability boost actually giving Porygon-Z two STABS (
with one of those being a STAB of your choosing). Basically - Porygon-Z stacking STABs go "brr" on your opponents.
Utility Parting Shot Spinner Morpeko

Morpeko @ Heavy-Duty Boots
Ability: Hunger Switch
Tera Type: Ghost
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Aura Wheel
- Parting Shot
- Rapid Spin
- Super Fang / Knock Off / Taunt / Seed Bomb
I've been advocating for and using Morpeko since its introduction in Generation 8. I feel that it's one of the most underrated Pokemon and the best of the Pika clones competitively. Aura Wheel is effectively two STAB moves in one (
Electric/Dark, 110 BP, 100% Acc) that boosts Morpeko's speed by one upon a successful hit (
switches between the types turn by turn) and that particular STAB combination is very nice in this meta. Parting Shot allows Morpeko to maintain momentum while softening any incoming blows for teammates thanks to the -1 to both Attack and Special Attack that your opponent gets, while Rapid Spin is useful as always. The last slot is a toss-up depending on your team's specific needs, but the four options I've listed are all options that I've tooled around with that are quite useful. Super Fang will take down half of the HP of particularly immovable feeling threats like Dondozo, but STAB Knock Off pairs quite nicely with Morpeko's other utility tools. Taunt is also a great option to shut down slower defensive and utility threats, while Seed Bomb provides good coverage against some nasty OU threats.