Primarina @ Life Orb  
Ability: Torrent  
Tera Type: Water  
EVs: 80 HP / 252 Def / 140 SpA / 36 Spe  
Modest Nature  
IVs: 0 Atk  
- Hydro Cannon  
- Moonblast  
- Icy Wind  
- Encore

Regidrago @ Choice Scarf  
Ability: Dragon's Maw  
Tera Type: Dragon  
EVs: 132 Atk / 124 SpA / 252 Spe  
Naive Nature  
- Outrage  
- Dragon Energy  
- Draco Meteor  
- Earthquake  

Pecharunt @ Choice Band  
Ability: Poison Puppeteer  
Tera Type: Poison  
EVs: 76 HP / 252 Atk / 180 Spe  
Adamant Nature  
- Poltergeist  
- Gunk Shot  
- Phantom Force  
- Malignant Chain

Prim and Drago are database sets (though I gave Prim 6.3s), Pecharunt outspeeds Corv, max Attack, rest in HP.