Weak toFighting ×1.6

Attacker	Type	Moveset	DPS
Lucario	FightingSteel	Force PalmAura SphereLegacy	43.1
Pheromosa	BugFighting	Low KickFocus Blast	39.5
Terrakion	RockFighting	Double KickSacred SwordLegacy	39.3
Blaziken	FireFighting	CounterAura Sphere	39.0
Kartana	GrassSteel	Fury CutterSacred Sword	37.2
Conkeldurr	Fighting	Force PalmFocus Blast	36.0
Keldeo	WaterFighting	Low KickSacred Sword	35.6
Breloom	GrassFighting	Force PalmDynamic Punch	35.5
Urshifu	Fighting	CounterDynamic Punch	35.2
Eternatus	PoisonDragon	Poison JabDynamax CannonLegacy	35.0
Marshadow	FightingGhost	CounterClose Combat	34.5
Mewtwo	Psychic	CounterFocus BlastLegacy	34.3

Overcast boosts the Fighting attacks above. Partly cloudy boosts Chansey.

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

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

Questions people ask

What is Chansey weak to in Pokémon GO?

Chansey takes 1.6 times from Fighting.

What's the best counter to Chansey?

Lucario with Force Palm and Aura Sphere, worth 43.1 damage per second against Chansey's own defense. The full ranking is above.