What does the Gentle nature do?

Gentle raises Sp. Def by 10% and lowers Defense by 10%.

What stat does Gentle increase?

Gentle increases Sp. Def by 10% and decreases Defense by 10%. HP is unaffected.

A Gentle Pokémon likes Bitter flavors (tied to Sp. Def) and dislikes Sour flavors (tied to Defense).

Yes. Use a Gentle Mint to apply the Gentle stat effect to any Pokémon without changing its displayed nature.

Nature

Raises Sp. Def, lowers Defense.

Raises Sp. Def +10%

Lowers Defense −10%

LikesBitter

DislikesSour

Special walls paired with physical-defense support.

Calm −Attack Sassy −Speed Careful −Sp. Atk

What does the Gentle nature do?: Gentle raises Sp. Def by 10% and lowers Defense by 10%.
What stat does Gentle increase?: Gentle increases Sp. Def by 10% and decreases Defense by 10%. HP is unaffected.
What flavor does a Gentle Pokémon like?: A Gentle Pokémon likes Bitter flavors (tied to Sp. Def) and dislikes Sour flavors (tied to Defense).
Can I change a Pokémon to Gentle?: Yes. Use a Gentle Mint to apply the Gentle stat effect to any Pokémon without changing its displayed nature.