Weak toRock ×2.56WaterElectric ×1.6

Attacker	Type	Moveset	DPS
Glimmora	RockPoison	Rock ThrowMeteor Beam	36.8
Rampardos	Rock	Smack DownRock Slide	36.5
Tyrantrum	RockDragon	Rock ThrowMeteor Beam	34.2
Gigalith	Rock	Lock OnMeteor BeamLegacy	34.1
Rhyperior	GroundRock	Smack DownRock WreckerLegacy	33.0
Terrakion	RockFighting	Smack DownRock Slide	32.4
Tyranitar	RockDark	Smack DownStone EdgeLegacy	31.2
Regieleki	Electric	Lock OnThunder CageLegacy	30.4
Lycanroc	Rock	Rock ThrowStone Edge	29.7
Aggron	SteelRock	Smack DownMeteor Beam	28.8
Aerodactyl	RockFlying	Rock ThrowRock Slide	28.5
Aurorus	RockIce	Rock ThrowMeteor Beam	28.4

Partly cloudy boosts the Rock attacks above. Clear and Windy boost Mega Charizard Y.

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

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

Questions people ask

What is Mega Charizard Y weak to in Pokémon GO?

Mega Charizard Y takes 2.56 times damage from Rock, and 1.6 times from Water and Electric.

What's the best counter to Mega Charizard Y?

Glimmora with Rock Throw and Meteor Beam, worth 36.8 damage per second against Mega Charizard Y's own defense. The full ranking is above.