Gyarados-Mega @ Lum Berry  
Ability: Huge Power  
EVs: 252 Atk / 252 Def / 4 SpD  
Brave Nature  
IVs: 0 Spe  
- Water Shuriken  
- Pursuit  
- Sucker Punch  
- Gastro Acid  

Diancie-Mega @ Focus Sash  
Ability: Pixilate  
EVs: 252 Atk / 4 SpA / 252 Spe  
Naughty Nature  
- Fake Out  
- Extreme Speed  
- Boomburst  
- Toxic Spikes  

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

Dusclops @ Safety Goggles  
Ability: Wonder Guard  
EVs: 252 HP / 252 Def / 4 SpD  
Relaxed Nature  
IVs: 0 Spe  
- King's Shield  
- Recover  
- Stealth Rock  
- U-turn  

Groudon-Primal @ Choice Band  
Ability: Mold Breaker  
EVs: 240 HP / 252 Atk / 16 Spe  
Adamant Nature  
- Precipice Blades  
- Thousand Arrows  
- V-create  
- U-turn  

Xerneas @ Leftovers  
Ability: Wonder Guard  
EVs: 180 Def / 252 SpA / 76 Spe  
Modest Nature  
IVs: 0 Atk  
- Substitute  
- Shell Smash  
- Moonblast  
- Baton Pass