Natures are a mechanic that influences how a Pokémon's stats grow.
A Pokémon's Nature is displayed on the Pokémon's summary screen. The stats affected by a Pokémon's Nature are highlighted on their summary screens: the increased stat is notated in red text and the decreased stat is notated in blue text. A Pokémon's Nature usually affects the value of two of its stats, ultimately increasing one of its non-HP stats (Attack, Defense, Special Attack, Special Defense, or Speed) by 10% and decreasing another by 10%.
Every Nature represents one of the 25 unique possible combinations of stat increase and decrease; thus, there are five Natures that have no effect on the Pokémon's stat growth as they technically increase and decrease the same stat (Bashful, Docile, Hardy, Quirky, and Serious).
When breeding two Pokémon, the holder of an Everstone will pass down its nature.
If the player has a Pokemon with the ability Synchronize in the 1st slot (even if fainted), any wild Pokemon encountered has a 50% chance of having the same Nature as it. This even affects encounters with certain Legendary Pokemon, but does not affect "Gift" Pokemon (Pokemon that are not caught via battle) such as Mystery Gift Pokemon, the Eevee recieved in Venesi City, etc.
List of Natures
|Nature||Increased Stat||Decreased Stat|
|Rash||Sp. Attack||Sp. Defense|
|Careful||Sp. Defense||Sp. Attack|