Weak toIce ×2.56RockDragonFairy ×1.6

Attacker	Type	Moveset	DPS
Eternatus	PoisonDragon	Dragon TailDynamax CannonLegacy	34.8
Chien-Pao	DarkIce	Powder SnowAvalanche	33.9
Baxcalibur	DragonIce	Ice FangAvalanche	33.8
Mamoswine	IceGround	Powder SnowAvalanche	32.2
Weavile	DarkIce	Ice ShardAvalanche	31.7
Glaceon	Ice	Frost BreathAvalanche	31.3
Kyurem	DragonIce	Dragon BreathGlaciateLegacy	30.1
Jynx	IcePsychic	Frost BreathAvalanche	29.5
Vanilluxe	Ice	Frost BreathAvalancheLegacy	28.9
Frosmoth	IceBug	Powder SnowIce Beam	28.1
Porygon-Z	Normal	Lock OnBlizzard	27.6
Mewtwo	Psychic	Psycho CutIce Beam	27.5

Snow boosts the Ice attacks above. Windy boosts Mega Rayquaza.

Level 40, 15 attack IV, costed against Mega Rayquaza's own defense and typing, one per evolution family.

Mega Rayquaza's moveset, stats and CP All counters Raid board

Questions people ask

What is Mega Rayquaza weak to in Pokémon GO?

Mega Rayquaza takes 2.56 times damage from Ice, and 1.6 times from Rock, Dragon and Fairy.

What's the best counter to Mega Rayquaza?

Eternatus with Dragon Tail and Dynamax Cannon, worth 34.8 damage per second against Mega Rayquaza's own defense. The full ranking is above.