A neutral nature like Quirky does nothing for your Pokemon's stats. Even if you can't decide which stat to lower, the 10% boost from a proper nature is too big to leave on the table. Chansey Supply sells Nature Mints for 20,000 Poke Dollars. Swap off Quirky before you start climbing ranked.

Quirky is a neutral nature with no stat change. For special walls, use Calm or Careful instead.
#PokemonNatureTierRoleAbilitySpe
1
Skarmory
Skarmory
STEELFLYING
CarefulABulky SupportKeeneye70
2CalmABulky SupportMagic Guard60
3
Magearna
Magearna
STEELFAIRY
CalmABulky SupportSoulheart65
4
Amoonguss
Amoonguss
GRASSPOISON
CalmABulky SupportRegenerator30
5
Heatran
Heatran
FIRESTEEL
CalmABulky SupportFlashfire77
Skarmory
Skarmory
STEEL FLYING
A
Nature
Careful
Role
Bulky Support
Ability
Keeneye
Spe
70
Clefable
Clefable
FAIRY
A
Nature
Calm
Role
Bulky Support
Ability
Magic Guard
Spe
60
Magearna
Magearna
STEEL FAIRY
A
Nature
Calm
Role
Bulky Support
Ability
Soulheart
Spe
65
Amoonguss
Amoonguss
GRASS POISON
A
Nature
Calm
Role
Bulky Support
Ability
Regenerator
Spe
30
Heatran
Heatran
FIRE STEEL
A
Nature
Calm
Role
Bulky Support
Ability
Flashfire
Spe
77
Quirky is a neutral nature — no stat is increased or decreased.
Competitive Role
No competitive advantage. A stat-boosting nature is almost always preferred.
How to Get
SynchronizeLead with a Quirky Pokemon that has the Synchronize ability. Wild Pokemon will match its nature. (Gen 3+)
BreedingGive the parent with Quirky nature an Everstone. The offspring will inherit it. (100% since Gen 5)
Nature MintUse a Quirky Mint to change stat effects to Quirky. The original nature name stays but stats change. (Gen 8+)
What does the Quirky nature do in Pokemon?
Quirky is a neutral nature. It doesn't raise or lower any stat, so your Pokemon's stats stay at their base values. In competitive terms, it's the same as having no nature effect at all.
Is Quirky nature good?
Neutral natures like Quirky are almost never the right call. Every competitive Pokemon benefits from at least one stat boost. Use an Adamant, Jolly, Modest, or Timid nature instead.
How do I get a Quirky nature Pokemon?
Three ways: (1) Breed with an Everstone on a Quirky parent. (2) Lead with a Synchronize Pokemon that has Quirky. (3) Just catch anything. There's a 1/25 chance it already has Quirky. But seriously, you probably want to change it.
When should you use a neutral nature?
Almost never. The only edge case is a Pokemon that uses physical moves, special moves, and needs every defensive stat and Speed. That Pokemon doesn't really exist in competitive. Even mixed attackers prefer Naive, Hasty, or another nature that at least boosts Speed.