Psychic Terrain Blocking priority (Sucker canceled) + Shell Smash Sash Weak Armor Polteigeist+ AV Hat helping keep the sash+ Hawlucha terrain abuser and dark type breaker for Polteageist, Mirror Armor Corv with Body Press for Bisharp and Steels.

Polteageist @ Focus Sash  
Ability: Weak Armor  
EVs: 4 Def / 252 SpA / 252 Spe  
Modest Nature  
IVs: 0 Atk  
- Giga Drain  
- Shell Smash  
- Shadow Ball  
- Psychic

Indeedee @ Terrain Extender  
Ability: Psychic Surge  
Shiny: Yes  
EVs: 252 SpA / 4 SpD / 252 Spe  
Modest Nature  
IVs: 0 Atk  
- Dazzling Gleam  
- Psychic  
- Mystical Fire  
- Tri Attack

Hawlucha @ Psychic Seed  
Ability: Unburden  
EVs: 80 HP / 252 Atk / 176 Spe  
Adamant Nature  
- Close Combat  
- Taunt  
- Acrobatics  
- Swords Dance

Hatterene (F) @ Assault Vest  
Ability: Magic Bounce  
EVs: 248 HP / 208 SpA / 52 Spe  
Modest Nature  
- Mystical Fire  
- Psychic  
- Draining Kiss  
- Nuzzle

Seismitoad @ Leftovers  
Ability: Water Absorb  
EVs: 248 HP / 252 Def / 8 SpD  
Bold Nature  
IVs: 0 Atk  
- Earth Power  
- Scald  
- Toxic  
- Stealth Rock

Corviknight (M) @ Leftovers  
Ability: Mirror Armor  
Shiny: Yes  
EVs: 248 HP / 80 Def / 180 SpD  
Careful Nature  
- U-turn  
- Roost  
- Defog  
- Body Press