#0383 · Gen 3 · Legendary

Groudon — Best counters

Weaknesses

	Pokémon	Fast move	Charged move	Weather	Score
1	Kyogre (Primal)	waterWaterfall	waterOrigin PulseELITE	Rainy	10012.9
2	Sceptile (Mega)	grassBullet Seed	grassFrenzy PlantELITE	Clear	9412.1
3	Kartana	grassRazor Leaf	grassLeaf Blade	Clear	8611.2
4	Swampert (Mega)	waterWater Gun	waterHydro CannonELITE	Rainy	8410.9
5	Kyurem (White)	iceIce Fang	iceBlizzard	Snow	8310.8
6	Blastoise (Mega)	waterWater Gun	waterHydro CannonELITE	Rainy	7810.1
7	Shaymin (Sky)	grassMagical Leaf	grassGrass Knot	Clear	7810.1
8	Gyarados (Mega)	waterWaterfall	waterHydro Pump	Rainy	7710.0
9	Sharpedo (Mega)	waterWaterfall	waterHydro Pump	Rainy	769.9
10	Kyogre	waterWaterfall	waterOrigin PulseELITE	Rainy	769.9
11	Venusaur (Mega)	grassVine Whip	grassFrenzy PlantELITE	Clear	769.9
12	Gardevoir (Mega)	grassMagical Leaf	iceTriple Axel	Snow · partial	769.8
13	Groudon (Primal)	groundMud Shot	grassSolar Beam	Clear	759.7
14	Roserade	grassMagical Leaf	grassLeaf Storm	Clear	739.4
15	Zarude	grassVine Whip	grassPower Whip	Clear	729.3
16	Eternatus	dragonDragon Tail	dragonDynamax CannonELITE	Windy	719.1
17	Kyurem (Black)	dragonDragon Tail	iceBlizzard	Snow · partial	709.1
18	Quaquaval	waterWater Gun	waterHydro CannonELITE	Rainy	709.1
19	Greninja	waterWater Shuriken	waterHydro CannonELITE	Rainy	699.0
20	Latios (Mega)	dragonDragon Breath	grassSolar Beam	Clear · partial	699.0

Groudon is weak to Water (×1.6), Grass (×1.6), Ice (×1.6).
Watch its Ground/Dragon/Fire/Grass moves — counters like Kyogre (Primal) and Sceptile (Mega) take super-effective damage from them.
Rainy weather boosts Water moves ×1.2 — the best time to battle Groudon.

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