#0095 · Gen 1

Onix — Best counters

Weaknesses

water×2.56 double weaknessgrass×2.56 double weaknessfighting×1.60ground×1.60steel×1.60ice×1.60

	Pokémon	Fast move	Charged move	Weather	Score
1	Kyogre (Primal)	waterWaterfall	waterOrigin PulseELITE	Rainy	10020.7
2	Sceptile (Mega)	grassBullet Seed	grassFrenzy PlantELITE	Clear	9419.4
3	Kartana	grassRazor Leaf	grassLeaf Blade	Clear	8617.9
4	Swampert (Mega)	waterWater Gun	waterHydro CannonELITE	Rainy	8417.4
5	Blastoise (Mega)	waterWater Gun	waterHydro CannonELITE	Rainy	7816.2
6	Shaymin (Sky)	grassMagical Leaf	grassGrass Knot	Clear	7816.2
7	Gyarados (Mega)	waterWaterfall	waterHydro Pump	Rainy	7716.0
8	Sharpedo (Mega)	waterWaterfall	waterHydro Pump	Rainy	7615.8
9	Kyogre	waterWaterfall	waterOrigin PulseELITE	Rainy	7615.8
10	Venusaur (Mega)	grassVine Whip	grassFrenzy PlantELITE	Clear	7615.8
11	Groudon (Primal)	groundMud Shot	grassSolar Beam	Clear	7515.5
12	Roserade	grassMagical Leaf	grassLeaf Storm	Clear	7315.1
13	Zarude	grassVine Whip	grassPower Whip	Clear	7214.9
14	Quaquaval	waterWater Gun	waterHydro CannonELITE	Rainy	7014.5
15	Greninja	waterWater Shuriken	waterHydro CannonELITE	Rainy	6914.4
16	Kingler	waterBubble	waterCrabhammer	Rainy	6914.2
17	Meowscarada	grassLeafage	grassFrenzy PlantELITE	Clear	6814.2
18	Decidueye	grassMagical Leaf	grassFrenzy PlantELITE	Clear	6713.9
19	Lucario (Mega)	fightingForce PalmELITE	fightingAura Sphere	Overcast	6713.9
20	Tapu Bulu	grassBullet Seed	grassGrass Knot	Clear	6713.9

Water and Grass hits for ×2.56 — Onix's Rock/Ground typing is double-weak, so those attackers outperform their score gap.
Watch its Rock/Normal/Ground/Steel/Dragon moves — counters like Sceptile (Mega) and Shaymin (Sky) take super-effective damage from them.
Rainy weather boosts Water moves ×1.2 — the best time to battle Onix.

Rankings are estimated cycle DPS (attack stat × move damage ÷ cycle time, with STAB and type effectiveness). Not a full battle simulation.