Gourgeist-L+Regigigas or Munchlax

Gourgeist-Large @ Colbur Berry
Ability: Frisk
EVs: 252 HP / 232 Def / 24 Spe
Bold Nature
IVs: 0 Atk
- Will-O-Wisp
- Synthesis
- Leech Seed
- Foul Play / Seed Bomb

Regigigas @ Leftovers
Ability: Slow Start
EVs: 248 HP / 244 SpD / 16 Spe
Careful Nature
- Substitute
- Toxic
- Knock Off
- Return

Munchlax @ Eviolite
Ability: Thick Fat
EVs: 252 HP / 4 Atk / 252 SpD
Careful Nature
- Curse
- Rest
- Sleep Talk
- Return / Body Slam / Chip Away