Ditto @ Choice Specs  
Ability: Imposter  
Happiness: 1  
EVs: 252 SpA  
Modest Nature  
IVs: 30 Atk  
- Transform  

Speed / Transfer (Magearna)  
Ability: Soul-Heart  
EVs: 92 Atk  
IVs: 0 Atk  
- Heart Swap  
- Agility  

Set up (Clefable) @ Red Card  
Ability: Cute Charm  
EVs: 252 HP / 252 Spe  
IVs: 0 Atk  
- Cosmic Power  
- Work Up  
- Soft-Boiled  
- Recycle  

Skill & Acc (Spinda)  
Ability: Contrary  
EVs: 56 HP  
Jolly Nature  
IVs: 0 Atk  
- Skill Swap  
- Mud-Slap  

Defog and Supress (Mew)  
Ability: Synchronize  
EVs: 76 HP  
IVs: 0 Atk  
- Gastro Acid  
- Volt Switch  
- Defog  
- Psychic Terrain  

Adaptability (Skrelp)  
Ability: Adaptability  
EVs: 60 HP  
Modest Nature  
- Flip Turn  
- Endure