Celesteela @ Leftovers  
Ability: Beast Boost  
Level: 50  
EVs: 244 HP / 44 Atk / 132 Def / 84 SpD / 4 Spe  
Careful Nature  
IVs: 0 SpA  
- Heavy Slam  
- Wide Guard  
- Leech Seed  
- Protect

Unown
Move options:
- offensive: Flamethrower, Air Slash
- supportive: Substitute, Toxic

Unown
Offensive calcs:
- 44 Atk Celesteela Heavy Slam (120 BP) vs. 0 HP / 4 Def Mega Meowstic-F: 150-176 (100.6 - 118.1%) -- guaranteed OHKO
Defensive calcs:
- +2 252 SpA Fairy Aura Mega Meowstic-F Moonblast vs. 244 HP / 84+ SpD Celesteela: 90-107 (44.3 - 52.7%) -- guaranteed 3HKO after Leftovers recovery
- 252 SpA Transistor Regieleki Thunderbolt vs. 244 HP / 84+ SpD Celesteela: 162-192 (79.8 - 94.5%) -- guaranteed 2HKO after Leftovers recovery
- 252 Atk Urshifu-Single Strike Wicked Blow vs. 244 HP / 132 Def Celesteela on a critical hit: 88-105 (43.3 - 51.7%) -- guaranteed 3HKO after Leftovers recovery