#0645 · Gen 5 · Legendary

Landorus (Therian) — Best counters

Weaknesses

ice×2.56 double weaknesswater×1.60

	Pokémon	Fast move	Charged move	Weather	Score
1	Kyurem (White)	iceIce Fang	iceBlizzard	Snow	10017.2
2	Baxcalibur	iceIce Fang	iceBlizzard	Snow	8214.1
3	Glalie (Mega)	iceIce Shard	iceAvalanche	Snow	8113.9
4	Kyogre (Primal)	waterWaterfall	iceBlizzard	Snow · partial	8013.9
5	Weavile	iceIce Shard	iceAvalanche	Snow	7813.4
6	Glaceon	iceIce Shard	iceAvalanche	Snow	7613.2
7	Mamoswine	icePowder Snow	iceAvalanche	Snow	7412.7
8	Abomasnow (Mega)	icePowder Snow	iceBlizzard	Snow	7412.7
9	Gardevoir (Mega)	grassMagical Leaf	iceTriple Axel	Snow · partial	7112.2
10	Jynx	iceFrost Breath	iceAvalanche	Snow	7112.2
11	Kyurem (Black)	dragonDragon Tail	iceBlizzard	Snow · partial	6912.0
12	Vanilluxe	iceFrost Breath	iceAvalancheELITE	Snow	6911.9
13	Porygon Z	normalLock On	iceBlizzard	Snow · partial	6811.8
14	Cetitan	iceIce Shard	iceAvalanche	Snow	6711.5
15	Avalugg (Hisui)	icePowder Snow	iceBlizzard	Snow	6611.3
16	Mewtwo	psychicPsycho Cut	iceIce Beam	Snow · partial	6511.3
17	Frosmoth	icePowder Snow	iceIce Beam	Snow	6511.2
18	Kyurem	dragonDragon Breath	iceGlaciateELITE	Snow · partial	6411.0
19	Swampert (Mega)	waterWater Gun	waterHydro CannonELITE	Rainy	6310.9
20	Mr Rime	iceIce Shard	iceTriple Axel	Snow	6310.9

Ice hits for ×2.56 — Landorus (Therian)'s Ground/Flying typing is double-weak, so those attackers outperform their score gap.
Watch its Ground/Psychic/Rock/Fighting moves — counters like Kyurem (White) and Baxcalibur take super-effective damage from them.
Snow weather boosts Ice moves ×1.2 — the best time to battle Landorus (Therian).
Not yet in GO: Chien Pao would rank in the top 5 with Powder Snow / Blizzard but hasn't been released.

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