Gyarados-Mega @ Lum Berry  
Ability: Huge Power  
EVs: 252 HP / 252 Atk / 4 Def  
Adamant Nature  
- Water Shuriken  
- Pursuit  
- Sucker Punch  
- Gastro Acid  

Giratina @ Safety Goggles  
Ability: Prankster  
EVs: 248 HP / 252 Def / 8 SpD  
Bold Nature  
IVs: 0 Atk  
- Destiny Bond  
- Encore  
- Curse  
- Recover  

Mewtwo-Mega-X @ Focus Sash  
Ability: Huge Power  
EVs: 252 Atk / 4 SpD / 252 Spe  
Adamant Nature  
- Fusion Bolt  
- Gunk Shot  
- King's Shield  
- Beat Up  

Mewtwo-Mega-X @ Focus Sash  
Ability: Huge Power  
EVs: 252 Atk / 4 SpD / 252 Spe  
Adamant Nature  
- Thousand Arrows  
- Close Combat  
- King's Shield  
- Sacred Fire  

Xerneas @ Iron Plate  
Ability: Wonder Guard  
EVs: 180 Def / 252 SpA / 76 Spe  
Modest Nature  
IVs: 0 Atk  
- Shell Smash  
- Judgment  
- Moonblast  
- Scald  

Arceus @ Safety Goggles  
Ability: Wonder Guard  
EVs: 248 HP / 244 Def / 16 Spe  
Bold Nature  
- Stealth Rock  
- Defog  
- Aromatherapy  
- Recover