#0890 · Gen 8 · Legendary

Eternatus — Best counters

Weaknesses

ground×1.60psychic×1.60ice×1.60dragon×1.60

	Pokémon	Fast move	Charged move	Weather	Score
1	Eternatus	dragonDragon Tail	dragonDynamax CannonELITE	Windy	10014.6
2	Rayquaza (Mega)	dragonDragon Tail	dragonBreaking SwipeELITE	Windy	9513.9
3	Alakazam (Mega)	psychicConfusion	psychicPsychicELITE	Windy	9213.4
4	Eternatus (Eternamax)	dragonDragon Tail	dragonDynamax CannonELITE	Windy	9013.2
5	Groudon (Primal)	groundMud Shot	groundPrecipice BladesELITE	Clear	8712.7
6	Garchomp (Mega)	dragonDragon Tail	groundEarthquake	Clear · partial	8712.7
7	Salamence (Mega)	dragonDragon Tail	dragonDraco Meteor	Windy	8212.0
8	Gardevoir (Mega)	psychicConfusion	psychicPsychic	Windy	8111.9
9	Gallade (Mega)	psychicConfusion	psychicPsychic	Windy	8111.9
10	Latios (Mega)	dragonDragon Breath	psychicPsychic	Windy	8011.7
11	Kyurem (Black)	dragonDragon Tail	iceBlizzard	Snow · partial	7911.6
12	Mewtwo	psychicConfusion	psychicPsystrikeELITE	Windy	7911.6
13	Hoopa (Unbound)	psychicConfusion	psychicPsychic	Windy	7811.3
14	Palkia (Origin)	dragonDragon Tail	dragonDraco Meteor	Windy	7611.0
15	Landorus (Therian)	groundMud Shot	groundSandsear StormELITE	Clear	7511.0
16	Palkia	dragonDragon Tail	dragonDraco Meteor	Windy	7410.8
17	Deoxys (Attack)	psychicZen Headbutt	psychicPsycho Boost	Windy	7410.8
18	Kyurem (White)	iceIce Fang	iceBlizzard	Snow	7410.8
19	Salamence	dragonDragon Tail	dragonDraco Meteor	Windy	7310.7
20	Rayquaza	dragonDragon Tail	dragonBreaking SwipeELITE	Windy	7210.5

Eternatus is weak to Ground (×1.6), Psychic (×1.6), Ice (×1.6), Dragon (×1.6).
Watch its Dragon/Poison/Fire moves — counters like Eternatus and Rayquaza (Mega) take super-effective damage from them.
Windy weather boosts Dragon moves ×1.2 — the best time to battle Eternatus.

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