Weak toGroundElectricPsychic ×1.6

Attacker	Type	Moveset	DPS
Regieleki	Electric	Lock OnThunder CageLegacy	30.8
Mewtwo	Psychic	ConfusionPsystrikeLegacy	28.0
Zeraora	Electric	Volt SwitchPlasma Fists	26.4
Zekrom	DragonElectric	Charge BeamFusion BoltLegacy	25.8
Xurkitree	Electric	Thunder ShockDischarge	25.5
Deoxys	Psychic	Zen HeadbuttThunderbolt	24.5
Alakazam	Psychic	ConfusionPsychicLegacy	23.9
Groudon	Ground	Mud ShotPrecipice BladesLegacy	23.2
Azelf	Psychic	ConfusionFuturesight	23.2
Hoopa	PsychicGhost	ConfusionPsychic	23.1
Espeon	Psychic	ConfusionPsychic	23.1
Regigigas	Normal	Zen HeadbuttCrush GripLegacy	23.0

Rainy boosts the Electric attacks above. Overcast and Rainy boost Tentacruel.

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

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

Questions people ask

What is Tentacruel weak to in Pokémon GO?

Tentacruel takes 1.6 times from Ground, Electric and Psychic.

What's the best counter to Tentacruel?

Regieleki with Lock On and Thunder Cage, worth 30.8 damage per second against Tentacruel's own defense. The full ranking is above.