I've decided it's time for me to post this:
Gen 9 NU Grassy Terrain Setter

Grookey @ Terrain Extender
Ability: Grassy Surge
Tera Type: Poison
EVs: 4 Atk / 252 Def / 252 Spe
Jolly Nature
- Grassy Glide
- U-turn
- Taunt
- Endeavor
Yes, that's right, a Grookey set that is meant to be used on Grassy Terrain teams in Gen 9 NU. The reason for this is because Thwackey has been banned from Gen 9 NU, so if you still want to use Grassy Terrain teams in Gen 9 NU, Grookey is the only auto setter left if you don't want to go the Manual route and use something like Arboliva to set Grassy Terrain. While Grookey is indeed worse than Thwackey, it still does the one job it needs to get done: setting terrain.
Grassy Glide is used as the Grass STAB to revenge kill weakened Pokemon. U-turn is used to allow Grookey to bring in a teammate that can utilize Grassy Terrain. Taunt allows Grookey to stop opposing Pokemon from setting up hazards or boosting their stats, which can be useful to help the Terrain sweepers. Endeavor is used for a cool tech that can allow Grookey to deal quite a bit of chip damage to opposing Pokemon should Grookey's HP get low, being useful to help enable a sweep from one of your sweepers on your team by wearing down a crucial check to said sweeper. Terrain Extender is used to extend the amount of turns you have to use Grassy Terrain. Tera Poison is the chosen Tera type since it is the Tera Type Thwackey would often use, though let's be real: It is only a filler here since this set is for a format that uses Tera, and you really should NOT be using your Tera on Grookey lmao.
Max speed EVs with Jolly Nature are used to make Grookey as fast as possible. This set uses 252 Defense EVs or 252 HP EVs since the Defense EVs let Grookey take physical hits better, and having less HP is useful for Endeavor.