Mewtwo-Mega-X @ Mewtwonite Y  
Ability: Magic Guard  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpA / 252 SpD / 252 Spe  
Hasty Nature  
- Photon Geyser  
- Mind Blown  
- High Jump Kick  
- Volt Tackle    

Marshadow @ Sitrus Berry  
Ability: Speed Boost  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe  
Adamant Nature  
- Poltergeist  
- Low Kick  
- Shore Up  
- Belly Drum  

Chansey @ Eviolite  
Ability: Imposter  
Hidden Power: Ice  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpA / 252 SpD  
Relaxed Nature  
IVs: 0 Spe  
- Whirlwind  
- Shore Up  
- U-turn  
- Final Gambit  

Giratina @ Leftovers  
Ability: Prankster  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe  
Impish Nature  
- Nuzzle  
- Leech Seed  
- Haze  
- Shore Up  

Regigigas @ Toxic Orb  
Ability: Poison Heal  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe  
Adamant Nature  
- Facade  
- Spectral Thief  
- Shadow Sneak  
- Shift Gear  

Magearna @ Power Herb  
Ability: Simple  
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe  
Modest Nature  
IVs: 0 Atk  
- Moonblast  
- Hidden Power [Fire]  
- Shore Up  
- Geomancy