#0025 · Gen 1

Pikachu (Rock Star) — Best counters

Weaknesses

	Pokémon	Fast move	Charged move	Weather	Score
1	Groudon (Primal)	groundMud Shot	groundPrecipice BladesELITE	Clear	10012.7
2	Garchomp (Mega)	groundMud Shot	groundEarthquake	Clear	8911.3
3	Landorus (Therian)	groundMud Shot	groundSandsear StormELITE	Clear	8611.0
4	Groudon	groundMud Shot	groundPrecipice BladesELITE	Clear	769.7
5	Swampert (Mega)	groundMud Shot	groundEarthquake	Clear	749.4
6	Excadrill	groundMud Slap	groundEarthquake	Clear	729.2
7	Eternatus	poisonPoison Jab	dragonDynamax CannonELITE	Windy · partial	729.2
8	Mamoswine	groundMud Slap	groundHigh Horsepower	Clear	719.0
9	Heracross (Mega)	fightingCounter	groundEarthquake	Clear · partial	708.9
10	Sceptile (Mega)	bugFury Cutter	groundEarthquake	Clear · partial	698.8
11	Regigigas	normalHidden Power	normalCrush GripELITE	Partly Cloudy	698.8
12	Rhyperior	groundMud Slap	groundEarthquake	Clear	688.7
13	Garchomp	groundMud Shot	groundEarthquake	Clear	688.7
14	Lucario (Mega)	fightingForce PalmELITE	fightingAura Sphere	Overcast	688.7
15	Rayquaza (Mega)	dragonDragon Tail	dragonBreaking SwipeELITE	Windy	688.7
16	Landorus (Incarnate)	groundMud Shot	groundEarth Power	Clear	678.5
17	Alakazam (Mega)	psychicConfusion	psychicPsychicELITE	Windy	668.4
18	Krookodile	groundMud Slap	groundEarthquake	Clear	658.3
19	Metagross (Mega)	bugFury Cutter	groundEarthquake	Clear · partial	658.3
20	Eternatus (Eternamax)	poisonPoison Jab	dragonDynamax CannonELITE	Windy · partial	658.3

Pikachu (Rock Star) is weak to Ground (×1.6).
Watch its Electric/Fairy/Steel moves — counters like Garchomp (Mega) and Mamoswine take super-effective damage from them.
Clear weather boosts Ground moves ×1.2 — the best time to battle Pikachu (Rock Star).

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