Weak toPoisonGrassElectric ×1.6

Attacker	Type	Moveset	DPS
Regieleki	Electric	Lock OnThunder CageLegacy	63.9
Zeraora	Electric	Volt SwitchPlasma Fists	54.8
Kartana	GrassSteel	Razor LeafLeaf Blade	54.7
Zekrom	DragonElectric	Charge BeamFusion BoltLegacy	53.6
Xurkitree	Electric	Thunder ShockDischarge	53.0
Eternatus	PoisonDragon	Poison JabSludge Bomb	50.8
Naganadel	PoisonDragon	Poison JabSludge Bomb	48.2
Roserade	GrassPoison	Magical LeafLeaf Storm	46.6
Deoxys	Psychic	Charge BeamThunderbolt	46.1
Electivire	Electric	Thunder ShockWild Charge	45.8
Nihilego	RockPoison	Poison JabSludge Bomb	45.8
Zarude	DarkGrass	Vine WhipPower Whip	45.7

Rainy boosts the Electric attacks above. Overcast and Rainy boost Marill.

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

Marill's moveset, CP and shiny All counters Raid board

Questions people ask

What is Marill weak to in Pokémon GO?

Marill takes 1.6 times from Poison, Grass and Electric.

What's the best counter to Marill?

Regieleki with Lock On and Thunder Cage, worth 63.9 damage per second against Marill's own defense. The full ranking is above.