+ by pokeisfun (copy and pastable)
chuggy sluggy (Gastrodon) @ Leftovers
Ability: Storm Drain
EVs: 252 HP / 252 Def / 4 Spe
Bold Nature
IVs: 0 Atk
- Scald
- Earth Power
- Toxic
- Recover
ding dong (Bronzong) @ Leftovers
Ability: Levitate
EVs: 252 HP / 4 Atk / 252 SpD
Sassy Nature
IVs: 0 Spe
- Stealth Rock
- Protect
- Toxic
- Gyro Ball
Gastrodon is clearly a solid counter to Noivern, Rotom-W, and Cobalion (since it doesn't run SD). Bronzong is a fairly solid counter to Noivern and Gardevoir.
Gastrodon also beats Doublade and Incineroar, but is pretty badly crippled by Toxic so you probably want a primary Incineroar switch in or a Cobalion on your team to deter Knock Off. Doublade is also countered but can still do lot with +2 CC and +2 Sneak. It actually does 99.9% damage max funnily enough (70.8% max with CC, 6.25% leftovers recovery, and 35.9% with Shadow Sneak). You'll probably want other responses to those mons.
This type of core seems to fit well on more defensive balance teams with Umbreon and Sylveon.