Weak toBugGhostDark ×1.6

Attacker	Type	Moveset	DPS
Blacephalon	FireGhost	AstonishShadow Ball	78.3
Pheromosa	BugFighting	Bug BiteBug Buzz	75.5
Darkrai	Dark	SnarlShadow Ball	70.5
Chandelure	GhostFire	HexShadow Ball	69.9
Gengar	GhostPoison	LickShadow BallLegacy	69.8
Absol	Dark	SnarlBrutal SwingLegacy	68.4
Eternatus	PoisonDragon	Poison JabDynamax CannonLegacy	66.8
Dragapult	DragonGhost	AstonishShadow Ball	66.7
Hoopa	PsychicGhost	AstonishShadow Ball	65.5
Lunala	PsychicGhost	Shadow ClawShadow Ball	65.4
Gholdengo	SteelGhost	HexShadow Ball	65.3
Zoroark	Dark	SnarlFoul Play	65.2

Fog boosts the Ghost attacks above. Windy boosts Flittle.

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

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

Questions people ask

What is Flittle weak to in Pokémon GO?

Flittle takes 1.6 times from Bug, Ghost and Dark.

What's the best counter to Flittle?

Blacephalon with Astonish and Shadow Ball, worth 78.3 damage per second against Flittle's own defense. The full ranking is above.