Mewtwo-Mega-X @ Fist Plate  
Ability: Huge Power  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpA / 252 SpD / 252 Spe  
Lonely Nature  
- Light That Burns the Sky  
- Photon Geyser  
- Mach Punch  
- First Impression  

Gengar-Mega @ Choice Scarf  
Ability: Parental Bond  
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe  
Modest Nature  
IVs: 2 Atk / 30 Def  
- Moongeist Beam  
- Hidden Power [Ice]  
- Secret Sword  
- U-turn  

Groudon-Primal @ Earth Plate  
Ability: Parental Bond  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpA / 252 SpD / 252 Spe  
Naughty Nature  
- Shell Smash  
- Sunsteel Strike  
- Sacred Fire  
- Judgment  

Yveltal @ Leftovers  
Ability: Prankster  
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe  
Bold Nature  
IVs: 0 Atk  
- Lovely Kiss  
- Milk Drink  
- Substitute  
- Baton Pass  

Dialga @ Leppa Berry  
Ability: Wonder Guard  
EVs: 252 HP / 252 Atk / 252 Def / 252 SpA / 252 SpD / 252 Spe  
Impish Nature  
- Extreme Evoboost  
- Heal Order  
- Recycle  
- Sunsteel Strike  

Blissey (F) @ Lum Berry  
Ability: Innards Out  
EVs: 252 HP / 252 Atk / 252 SpD  
Gentle Nature  
IVs: 0 Def / 0 Spe  
- Magic Coat  
- Shore Up  
- Whirlwind  
- U-turn