Mega Gyarados Sweep

Sylveon @ Leftovers
Ability: Pixilate
EVs: 252 HP / 4 SpA / 252 SpD
Calm Nature
IVs: 30 SpA / 30 SpD
- Hyper Voice
- Wish
- Heal Bell
- Protect

Gyarados @ Gyaradosite
Ability: Intimidate
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Dragon Dance
- Waterfall
- Crunch
- Earthquake

Ferrothorn @ Rocky Helmet
Ability: Iron Barbs
EVs: 248 HP / 8 Atk / 252 Def
Impish Nature
- Thunder Wave
- Leech Seed
- Protect
- Power Whip

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

Latias (F) @ Life Orb
Ability: Levitate
EVs: 72 HP / 184 SpA / 252 Spe
Timid Nature
- Defog
- Draco Meteor
- Psyshock
- Thunderbolt

Talonflame @ Sharp Beak
Ability: Gale Wings
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Brave Bird
- Flare Blitz
- Roost
- Swords Dance