Weak toGroundRockElectric ×1.6

Attacker	Type	Moveset	DPS
Regieleki	Electric	Lock OnThunder CageLegacy	29.9
Zeraora	Electric	Volt SwitchPlasma Fists	25.6
Zekrom	DragonElectric	Charge BeamFusion BoltLegacy	25.1
Xurkitree	Electric	Thunder ShockDischarge	24.8
Glimmora	RockPoison	Rock ThrowMeteor Beam	22.6
Groudon	Ground	Mud ShotPrecipice BladesLegacy	22.5
Rampardos	Rock	Smack DownRock Slide	22.4
Eternatus	PoisonDragon	Poison JabDynamax CannonLegacy	21.7
Deoxys	Psychic	Charge BeamThunderbolt	21.6
Gigalith	Rock	Lock OnMeteor BeamLegacy	21.5
Electivire	Electric	Thunder ShockWild Charge	21.4
Excadrill	GroundSteel	Mud SlapEarthquake	21.4

Rainy boosts the Electric attacks above. Clear and Rainy boost Volcanion.

Level 40, 15 attack IV, costed against Volcanion's own defense and typing, one per evolution family.

Volcanion's moveset, CP and shiny All counters Raid board

Questions people ask

What is Volcanion weak to in Pokémon GO?

Volcanion takes 1.6 times from Ground, Rock and Electric.

What's the best counter to Volcanion?

Regieleki with Lock On and Thunder Cage, worth 29.9 damage per second against Volcanion's own defense. The full ranking is above.