Giratina @ Leftovers  
Ability: Arena Trap  
EVs: 248 HP / 8 SpD / 252 Spe  
Timid Nature  
IVs: 0 Atk  
- Substitute  
- Baton Pass  
- Acupressure  
- Encore  

Regigigas @ Mental Herb  
Ability: Mold Breaker  
EVs: 252 Atk / 4 SpD / 252 Spe  
Adamant Nature  
- Dark Void  
- Extreme Speed  
- Shell Smash  
- Bonemerang  

Mewtwo-Mega-X @ Eject Button  
Ability: Mold Breaker  
EVs: 252 Atk / 4 SpD / 252 Spe  
Jolly Nature  
- Knock Off  
- Close Combat  
- Parting Shot  
- Gastro Acid  

Mewtwo-Mega-Y @ Choice Scarf  
Ability: Arena Trap  
EVs: 252 SpA / 4 SpD / 252 Spe  
Timid Nature  
IVs: 0 Atk  
- Trick  
- Encore  
- Parting Shot  
- Psycho Boost  

Xerneas @ Choice Scarf  
Ability: Arena Trap  
EVs: 252 HP / 4 SpD / 252 Spe  
Timid Nature  
IVs: 0 Atk  
- Trick  
- Disable  
- Parting Shot  
- Defog  

Gyarados-Mega @ Shed Shell  
Ability: Wonder Guard  
EVs: 248 HP / 4 Atk / 252 SpD  
Careful Nature  
- Baton Pass  
- Beat Up  
- Roost  
- Spikes