Trick Room

Gyarados-Mega @ Gyaradosite
Ability: Mold Breaker
EVs: 20 HP / 252 Atk / 236 Spe
Jolly Nature
- Waterfall
- Crunch
- Dragon Dance
- Protect

Terrakion @ Focus Sash
Ability: Justified
EVs: 56 HP / 252 Atk / 200 Spe
Jolly Nature
- Rock Slide
- Close Combat
- Poison Jab
- Protect

Heatran @ Shuca Berry
Ability: Flash Fire
EVs: 252 HP / 252 SpA / 4 SpD
Modest Nature
IVs: 0 Atk
- Heat Wave
- Earth Power
- Flash Cannon
- Protect

Landorus-Therian @ Assault Vest
Ability: Intimidate
EVs: 252 HP / 12 Def / 196 SpA / 48 SpD
Modest Nature
- Earth Power
- U-turn
- Sludge Bomb
- Hidden Power [Ice]

Mew @ Sitrus Berry
Ability: Synchronize
EVs: 252 HP / 24 Def / 88 SpA / 144 SpD
Sassy Nature
IVs: 0 Atk / 0 Spe
- Trick Room
- Ice Beam
- Psychic
- Volt Switch

Amoonguss @ Rocky Helmet
Ability: Regenerator
EVs: 252 HP / 172 Def / 84 SpD
Relaxed Nature
IVs: 0 Atk / 0 Spe
- Rage Powder
- Spore
- Giga Drain
- Foul Play