Ditto @ Choice Scarf  
Ability: Imposter  
EVs: 252 HP / 4 Atk / 252 Def  
Relaxed Nature  
IVs: 0 Spe  
- Transform  

Groudon @ Leftovers  
Ability: Drought  
EVs: 240 HP / 16 Atk / 156 Def / 96 Spe  
Adamant Nature  
- Stealth Rock  
- Swords Dance  
- Precipice Blades  
- Stone Edge  

Mewtwo @ Expert Belt  
Ability: Pressure  
EVs: 252 SpA / 4 SpD / 252 Spe  
Timid Nature  
IVs: 0 Atk  
- Psystrike  
- Fire Blast  
- Recover  
- Ice Beam  

Necrozma-Dusk-Mane @ Rocky Helmet  
Ability: Prism Armor  
EVs: 252 HP / 188 Def / 68 Spe  
Impish Nature  
- Dragon Dance  
- Sunsteel Strike  
- Knock Off  
- Morning Sun  

Eternatus @ Black Sludge  
Ability: Pressure  
EVs: 176 HP / 236 SpD / 96 Spe  
Timid Nature  
- Toxic Spikes  
- Mystical Fire  
- Recover  
- Dragon Tail  

Yveltal @ Heavy-Duty Boots  
Ability: Dark Aura  
EVs: 248 HP / 20 Def / 44 SpD / 196 Spe  
Jolly Nature  
- Knock Off
- Roost  
- Defog  
- U-turn