Weak toFlyingRockFirePsychic ×1.6

Attacker	Type	Moveset	DPS
Blacephalon	FireGhost	IncinerateMind BlownLegacy	44.6
Mewtwo	Psychic	ConfusionPsystrikeLegacy	38.5
Reshiram	DragonFire	Fire FangFusion FlareLegacy	37.0
Salamence	DragonFlying	Fire FangFly	34.2
Chandelure	GhostFire	Fire SpinOverheat	33.9
Moltres	FireFlying	Fire SpinFly	33.6
Cinderace	Fire	Fire SpinPyroball	33.5
Volcarona	BugFire	Fire SpinOverheat	33.1
Darmanitan	Fire	Fire FangOverheat	33.0
Yveltal	DarkFlying	GustOblivion WingLegacy	32.9
Alakazam	Psychic	ConfusionPsychicLegacy	32.8
Toucannon	NormalFlying	PeckBeak BlastLegacy	32.6

Clear boosts the Fire attacks above. Overcast and Rainy boost Mega Beedrill.

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

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

Questions people ask

What is Mega Beedrill weak to in Pokémon GO?

Mega Beedrill takes 1.6 times from Flying, Rock, Fire and Psychic.

What's the best counter to Mega Beedrill?

Blacephalon with Incinerate and Mind Blown, worth 44.6 damage per second against Mega Beedrill's own defense. The full ranking is above.