Mega Aggron in OU

Aggron @ Aggronite
Ability: Sturdy
EVs: 252 HP / 16 Def / 240 SpD
Impish Nature
- Stealth Rock
- Heavy Slam
- Avalanche
- Fire Punch

Sylveon @ Leftovers
Ability: Pixilate
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Hyper Voice
- Heal Bell
- Wish
- Protect

Dragonite @ Weakness Policy
Ability: Multiscale
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Dragon Dance
- Outrage
- Extreme Speed
- Earthquake

Latios @ Life Orb
Ability: Levitate
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Draco Meteor
- Psyshock
- Recover
- Defog

Keldeo @ Choice Specs
Ability: Justified
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Scald
- Secret Sword
- Hydro Pump
- Icy Wind

Landorus-Therian @ Choice Scarf
Ability: Intimidate
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Earthquake
- U-turn
- Stone Edge
- Knock Off