What does the Bold nature do?

Bold raises Defense by 10% and lowers Attack by 10%.

What stat does Bold increase?

Bold increases Defense by 10% and decreases Attack by 10%. HP is unaffected.

A Bold Pokémon likes Sour flavors (tied to Defense) and dislikes Spicy flavors (tied to Attack).

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

Nature

Raises Defense, lowers Attack.

Raises Defense +10%

Lowers Attack −10%

LikesSour

DislikesSpicy

Physical walls that rely on status/special moves, not physical attacks.

Relaxed −Speed Impish −Sp. Atk Lax −Sp. Def

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