Weak toBugGhostDark ×1.6

Attacker	Type	Moveset	DPS
Blacephalon	FireGhost	AstonishShadow Ball	81.6
Pheromosa	BugFighting	Bug BiteBug Buzz	78.7
Darkrai	Dark	SnarlShadow Ball	73.4
Chandelure	GhostFire	HexShadow Ball	72.8
Gengar	GhostPoison	LickShadow BallLegacy	72.7
Absol	Dark	SnarlBrutal SwingLegacy	71.2
Eternatus	PoisonDragon	Poison JabDynamax CannonLegacy	69.6
Dragapult	DragonGhost	AstonishShadow Ball	69.5
Hoopa	PsychicGhost	AstonishShadow Ball	68.2
Lunala	PsychicGhost	Shadow ClawShadow Ball	68.1
Gholdengo	SteelGhost	HexShadow Ball	68.0
Zoroark	Dark	SnarlFoul Play	67.9

Fog boosts the Ghost attacks above. Windy boosts Cosmog.

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

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

Questions people ask

What is Cosmog weak to in Pokémon GO?

Cosmog takes 1.6 times from Bug, Ghost and Dark.

What's the best counter to Cosmog?

Blacephalon with Astonish and Shadow Ball, worth 81.6 damage per second against Cosmog's own defense. The full ranking is above.