Rain is Pain

Forretress @ Leftovers
Ability: Sturdy
EVs: 252 HP / 4 Atk / 252 Def
Relaxed Nature
IVs: 0 Spe
- Gyro Ball
- Volt Switch
- Stealth Rock
- Rapid Spin

Swampert-Mega @ Swampertite
Ability: Damp
EVs: 104 HP / 252 Atk / 152 Spe
Adamant Nature
- Waterfall
- Earthquake
- Ice Punch
- Rain Dance

Hydreigon @ Choice Scarf
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Dark Pulse
- Draco Meteor
- U-turn
- Flamethrower

Entei @ Choice Band
Ability: Pressure
Shiny: Yes
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Sacred Fire
- Flare Blitz
- Stone Edge
- Extreme Speed

Toxicroak @ Lum Berry
Ability: Dry Skin
EVs: 112 HP / 252 Atk / 4 SpD / 140 Spe
Adamant Nature
- Drain Punch
- Poison Jab
- Sucker Punch
- Swords Dance

Sylveon @ Leftovers
Ability: Pixilate
EVs: 252 HP / 4 SpA
Calm Nature
IVs: 0 Atk
- Hyper Voice
- Protect
- Wish
- Heal Bell