Weak toGrassElectric ×1.6

Attacker	Type	Moveset	DPS
Regieleki	Electric	Lock OnThunder CageLegacy	27.4
Zeraora	Electric	Volt SwitchPlasma Fists	23.5
Kartana	GrassSteel	Razor LeafLeaf Blade	23.4
Zekrom	DragonElectric	Charge BeamFusion BoltLegacy	23.0
Xurkitree	Electric	Thunder ShockDischarge	22.7
Roserade	GrassPoison	Magical LeafLeaf Storm	20.0
Eternatus	PoisonDragon	Poison JabDynamax CannonLegacy	19.9
Deoxys	Psychic	Charge BeamThunderbolt	19.8
Electivire	Electric	Thunder ShockWild Charge	19.6
Zarude	DarkGrass	Vine WhipPower Whip	19.6
Rillaboom	Grass	Razor LeafFrenzy PlantLegacy	19.4
Raikou	Electric	Volt SwitchWild Charge	19.1

Rainy boosts the Electric attacks above. Rainy boosts Mega Blastoise.

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

Mega Blastoise's moveset, stats and CP All counters Raid board

Questions people ask

What is Mega Blastoise weak to in Pokémon GO?

Mega Blastoise takes 1.6 times from Grass and Electric.

What's the best counter to Mega Blastoise?

Regieleki with Lock On and Thunder Cage, worth 27.4 damage per second against Mega Blastoise's own defense. The full ranking is above.