Weak toBugGhostDark ×1.6

Attacker	Type	Moveset	DPS
Blacephalon	FireGhost	AstonishShadow Ball	22.9
Pheromosa	BugFighting	Bug BiteBug Buzz	22.0
Darkrai	Dark	SnarlShadow Ball	20.6
Chandelure	GhostFire	HexShadow Ball	20.4
Gengar	GhostPoison	LickShadow BallLegacy	20.4
Absol	Dark	SnarlBrutal SwingLegacy	20.0
Eternatus	PoisonDragon	Poison JabDynamax CannonLegacy	19.5
Dragapult	DragonGhost	AstonishShadow Ball	19.5
Hoopa	PsychicGhost	AstonishShadow Ball	19.1
Lunala	PsychicGhost	Shadow ClawShadow Ball	19.1
Gholdengo	SteelGhost	HexShadow Ball	19.1
Zoroark	Dark	SnarlFoul Play	19.0

Fog boosts the Ghost attacks above. Windy boosts Cosmoem.

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

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

Questions people ask

What is Cosmoem weak to in Pokémon GO?

Cosmoem takes 1.6 times from Bug, Ghost and Dark.

What's the best counter to Cosmoem?

Blacephalon with Astonish and Shadow Ball, worth 22.9 damage per second against Cosmoem's own defense. The full ranking is above.