Natures
Docile does not change any stat. A Pokémon with this nature has exactly the values that follow from its base stats, IVs and EVs.
A neutral nature. Safe for a Pokémon whose set uses every stat, but in ranked battles it usually wastes an opportunity.
Flavor
None — a neutral nature has no liked or disliked flavor. That is convenient with Poffins and Pokéblocks: such a Pokémon eats anything without complaint, so healing never works worse.