#0073 · Gen 1

Tentacruel — Best counters

Weaknesses

	Pokémon	Fast move	Charged move	Weather	Score
1	Alakazam (Mega)	psychicConfusion	psychicPsychicELITE	Windy	10013.4
2	Regieleki	normalLock On	electricThunder CageELITE	Rainy · partial	10013.3
3	Deoxys (Attack)	psychicZen Headbutt	electricZap Cannon	Rainy · partial	9512.8
4	Groudon (Primal)	groundMud Shot	groundPrecipice BladesELITE	Clear	9512.7
5	Gardevoir (Mega)	psychicConfusion	psychicPsychic	Windy	8911.9
6	Gallade (Mega)	psychicConfusion	psychicPsychic	Windy	8911.9
7	Mewtwo	psychicConfusion	psychicPsystrikeELITE	Windy	8711.6
8	Latios (Mega)	psychicZen Headbutt	psychicPsychic	Windy	8611.5
9	Hoopa (Unbound)	psychicConfusion	psychicPsychic	Windy	8511.3
10	Garchomp (Mega)	groundMud Shot	groundEarthquake	Clear	8411.3
11	Landorus (Therian)	groundMud Shot	groundSandsear StormELITE	Clear	8211.0
12	Manectric (Mega)	electricThunder Fang	electricWild Charge	Rainy	8211.0
13	Xurkitree	electricThunder Shock	electricDischarge	Rainy	8010.8
14	Ampharos (Mega)	electricVolt Switch	electricZap Cannon	Rainy	7910.5
15	Zekrom	electricCharge Beam	electricFusion BoltELITE	Rainy	7710.3
16	Deoxys (Normal)	psychicZen Headbutt	electricThunderbolt	Rainy · partial	7710.3
17	Metagross (Mega)	psychicZen Headbutt	psychicPsychic	Windy	7710.3
18	Latias (Mega)	psychicZen Headbutt	psychicPsychic	Windy	749.9
19	Alakazam	psychicConfusion	psychicPsychicELITE	Windy	749.9
20	Groudon	groundMud Shot	groundPrecipice BladesELITE	Clear	739.7

Tentacruel is weak to Ground (×1.6), Electric (×1.6), Psychic (×1.6).
Watch its Poison/Water/Ice moves — counters like Groudon (Primal) and Gardevoir (Mega) take super-effective damage from them.
Windy weather boosts Psychic moves ×1.2 — the best time to battle Tentacruel.

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