Weak toGroundGhostFireDark ×1.6

Attacker	Type	Moveset	DPS
Blacephalon	FireGhost	IncinerateMind BlownLegacy	29.9
Reshiram	DragonFire	Fire FangFusion FlareLegacy	24.9
Chandelure	GhostFire	Fire SpinOverheat	22.8
Cinderace	Fire	Fire SpinPyroball	22.4
Volcarona	BugFire	Fire SpinOverheat	22.2
Darmanitan	Fire	Fire FangOverheat	22.1
Darkrai	Dark	SnarlShadow Ball	21.8
Gengar	GhostPoison	LickShadow BallLegacy	21.6
Blaziken	FireFighting	Fire SpinBlast BurnLegacy	21.4
Groudon	Ground	Mud ShotPrecipice BladesLegacy	21.4
Moltres	FireFlying	Fire SpinOverheat	21.2
Absol	Dark	SnarlBrutal SwingLegacy	21.1

Clear boosts the Fire attacks above. Snow and Windy boost Metagross.

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

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

Questions people ask

What is Metagross weak to in Pokémon GO?

Metagross takes 1.6 times from Ground, Ghost, Fire and Dark.

What's the best counter to Metagross?

Blacephalon with Incinerate and Mind Blown, worth 29.9 damage per second against Metagross's own defense. The full ranking is above.