Gen 8 NU

Sirfetch’d @ Leek
Ability: Scrappy
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- First Impression
- Close Combat
- Knock Off / Brave Bird
- Steel Wing
A set that is meant for luring and taking out Diancie. First Impression allows you to revenge kill Pokemon like Starmie, Celebi, and Rotom-C, and also allows you to revenge kill weakened Pokémon such as Shell Smash Blastoise if put into range of getting KOed by it. Close Combat is STAB and also hits ghost types thanks to Scrappy. Knock Off is for removing items from opposing Pokémon and is also useful against switch ins like Garbodor and Talonflame (provided you don't get burned). Brave Bird can be used instead for hitting Pokemon like Araquanid, Vileplume, and Toxicroak super effectively. Steel Wing is for hitting fairies and allows to you to 2HKO physically defensive Diancie, and can OHKO it if you get enough chip damage onto it, in this case, at least two times of switching into Stealth Rock.
Teammates
Sirfetch'd loves steel types, meaning Pokemon such as Ninjask, Xatu, and Dragalge can lure in steel types and pivot on them to bring in Sirfetch'd. Flygon is also a good partner since it can use U-Turn to bring in Sirfetch'd. Rotom-C is also a good partner for Sirfetch'd, as it can deal with Mantine, a Pokemon who resists Close Combat.