Gen 9 NU Shell Smash Grassy Terrain Sweeper

Torterra @ Clear Amulet / Life Orb
Ability: Overgrow
Tera Type: Ghost
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Shell Smash
- Grassy Glide
- Headlong Rush
- Tera Blast
The Shell Smash set Torterra currently uses in Gen 9 NU. Torterra is usually found on Sticky Web teams to help out with speed issues. However, with Cinccino, Scale Shot Flygon, and even Flamigo making Sticky Web as a playstyle sad, Torterra finds success on another playstyle: Grassy Terrain. This is because of Torterra having access to Grassy Glide.
With Shell Smash boosting its attack and speed stats, Torterra can turn into a potent sweeper once its checks are weakened or knocked out. Since this set is used with Grassy Terrain, Grassy Glide is used for the Grass STAB since it gets priority while Grassy Terrain is up. Torterra appreciates Grassy Glide's priority, since Torterra isn't that fast at +2 Speed, and it actually allows Torterra to revenge kill Choice Scarf Pokemon such as Flygon (provided it doesn't Tera Steel) and Porygon-Z, as well as boosted Pokemon such as Cinccino and Agility Porygon-Z sets.
Headlong Rush is used for the Ground STAB to hit Pokemon who resist Grassy Glide such as Chandelure, Klefki, Munkidori, Copperajah, Alolan Muk, Toxtricity, Incineroar, and Overqwil for super effective damage, and Amoonguss for neutral damage, and is used over Earthquake since Headlong Rush's power doesn't get halved when Grassy Terrain is up.
Tera Blast Ghost is used to allow Torterra to hit Pokemon Bronzong, Decidueye, and Brambleghast super effectively, as well as Pokemon such as Flamigo, Altaria, Kilowattrel, Scyther, and Tornadus for neutral damage. Tera Blast Ghost being able to OHKO Flamigo at +2 is why Torterra prefers Tera Blast Ghost over Crunch to hit Pokemon who resist both of Torterra's STABs.
Overgrow is used for the Ability to potentially allow Torterra to have stronger Grassy Glides. Adamant Nature is used to allow Torterra to have as much breaking power as possible. In addition to Tera Blast Ghost, Tera Ghost is also useful defensively, being immune to Normal and Fighting moves, resist Poison moves, and Bug moves to prevent Torterra from being revenge killed by First Impression Flygon. Clear Amulet allows Torterra to have a way to prevent Intimidate from working on it provided you don't have your item knocked off. Life Orb can be used instead to give Torterra's attacks more power, being useful to secure an OHKO against Amoonguss:
+2 252+ Atk Life Orb Torterra Headlong Rush vs. 252 HP / 212+ Def Amoonguss: 464-547 (107.4 - 126.6%) -- guaranteed OHKO
You also OHKO max max Physically Defensive Amoonguss with +2 Life Orb Headlong Rush:
+2 252+ Atk Life Orb Torterra Headlong Rush vs. 252 HP / 252+ Def Amoonguss: 445-524 (103 - 121.2%) -- guaranteed OHKO
Life Orb can also allow base (Normal) Tera Blast to 2HKO Avalugg if you want to punish it for switching in.
Since this set is to be used on Grassy Terrain teams, Thwackey is a required teammate since it sets up Grassy Terrain to enable this Torterra set. Since this set is on Grassy Terrain teams, this means Torterra can be seen alongside other setup sweepers that benefit from Grassy Terrain such as Oricorio-Pa'u, Grafaiai, Arcanine, Firebull/Redbull (
), and Hitmonlee.