Weak toWaterGrass ×2.56FightingGroundSteelIce ×1.6

Attacker	Type	Moveset	DPS
Kartana	GrassSteel	Razor LeafLeaf Blade	38.2
Inteleon	Water	Water GunHydro CannonLegacy	34.5
Kyogre	Water	WaterfallOrigin PulseLegacy	34.3
Roserade	GrassPoison	Magical LeafLeaf Storm	32.6
Kingler	Water	BubbleCrabhammer	32.6
Greninja	WaterDark	Water ShurikenHydro CannonLegacy	32.5
Zarude	DarkGrass	Vine WhipPower Whip	32.0
Rillaboom	Grass	Razor LeafFrenzy PlantLegacy	31.6
Quaquaval	WaterFighting	Water GunHydro CannonLegacy	31.2
Breloom	GrassFighting	Force PalmGrass KnotLegacy	31.0
Meowscarada	GrassDark	LeafageFrenzy PlantLegacy	30.8
Primarina	WaterFairy	WaterfallHydro CannonLegacy	30.7

Rainy boosts the Water attacks above. Clear and Partly cloudy boost Onix.

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

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

Questions people ask

What is Onix weak to in Pokémon GO?

Onix takes 2.56 times damage from Water and Grass, and 1.6 times from Fighting, Ground, Steel and Ice.

What's the best counter to Onix?

Kartana with Razor Leaf and Leaf Blade, worth 38.2 damage per second against Onix's own defense. The full ranking is above.