#0642 · Gen 5 · Legendary

Thundurus (Therian) — Best counters

Weaknesses

rock×1.60ice×1.60

	Pokémon	Fast move	Charged move	Weather	Score
1	Diancie (Mega)	rockRock Throw	rockRock Slide	Partly Cloudy	10011.5
2	Kyurem (White)	iceIce Fang	iceBlizzard	Snow	9410.8
3	Tyranitar (Mega)	rockSmack DownELITE	rockStone Edge	Partly Cloudy	8910.2
4	Aerodactyl (Mega)	rockRock Throw	rockRock Slide	Partly Cloudy	859.8
5	Rampardos	rockSmack Down	rockRock Slide	Partly Cloudy	849.7
6	Eternatus	poisonPoison Jab	dragonDynamax CannonELITE	Windy · partial	809.2
7	Kyurem (Black)	dragonDragon Tail	iceBlizzard	Snow · partial	799.1
8	Tyrantrum	rockRock Throw	rockMeteor Beam	Partly Cloudy	789.0
9	Baxcalibur	iceIce Fang	iceBlizzard	Snow	778.8
10	Regigigas	normalHidden Power	normalCrush GripELITE	Partly Cloudy	778.8
11	Glalie (Mega)	iceIce Shard	iceAvalanche	Snow	768.7
12	Rayquaza (Mega)	dragonDragon Tail	rockAncient Power	Partly Cloudy · partial	768.7
13	Kyogre (Primal)	waterWaterfall	iceBlizzard	Snow · partial	768.7
14	Rhyperior	rockSmack Down	rockRock WreckerELITE	Partly Cloudy	758.6
15	Regieleki	normalLock On	electricThunder CageELITE	Rainy · partial	758.6
16	Gigalith	rockSmack Down	rockMeteor BeamELITE	Partly Cloudy	758.6
17	Terrakion	rockSmack Down	rockRock Slide	Partly Cloudy	748.5
18	Gardevoir (Mega)	fairyCharm	iceTriple Axel	Snow · partial	738.4
19	Weavile	iceIce Shard	iceAvalanche	Snow	738.4
20	Alakazam (Mega)	psychicConfusion	psychicPsychicELITE	Windy	738.4

Thundurus (Therian) is weak to Rock (×1.6), Ice (×1.6).
Watch its Dark/Electric/Poison/Fighting moves — counters like Kyurem (White) and Tyranitar (Mega) take super-effective damage from them.
Partly Cloudy weather boosts Rock moves ×1.2 — the best time to battle Thundurus (Therian).

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