Natures (Generation III and are carried through as a game mechanic through Generation IV and Generation V. Each Pokémon has the potential to have one of the 25 natures available which are listed and described below.) are an element of gameplay that was introduced in
Natures only effect the growth of 2 of it's stats, ultimately raising one to 110% of it's total power and decreasing one to only 90% of its total power, not only that but they determine the type of flavour that the Pokémon will like and dislike. Each Natures are 'tagged' to a specific flavour, for example, a Pokémon who has a Relaxed Nature likes Sour but dislikes Sweet, and as such, since the Nature boosts that stat, all Natures that boost that stat alone will have the same favoured flavor (e.g For Pokémon with a Nature that increases Defense, all Pokémon with one of those Natures will like the flavour of Sour). The same applies for those that dislike a certain flavour, which is dependant of what stat the Nature decreases. Again, for example, if a Pokémon had a Nature that decreased it's Defense rather than increased it, it would dislike the Sour Flavour.
Each of the 25 Natures holds a unique combination of Stats that they can increase and decrease and as such no two natures have the same effect -- the exception being to the 5 Natures that have no effect on any of the 5 stats (Hardy, Docile, Quirky, Serious, and Bashful).
As of Pokémon Emerald a Ditto or any Female Pokémon that holds an Everstone has a 50% chance of passing down its own Nature unto its offspring when placed in the Day Care with a Male (or a Ditto (Note that two Dittos cannot breed together, as the same applies to all other Genderless Pokémon that are able to breed with other, gendered, Pokémon)) but only if both Trainer and Pokémon come from the same languaged game. Another addition added in Emerald was that, if a Pokémon with the ability Synchronize was in the lead spot of the party, it would experience a 50% chance of finding a Wild Pokémon with an identical nature. This doesn't include stationary legendaries however, but does work for all other Pokémon, the exceptions being experienced in Generation IV within HeartGold and SoulSilver in which the NPC given Eevee by Bill, Fossils resurrected from the Museum and when capturing a Pokémon in the Pokéwalker.
Natures are also a factor in the way a Pokémon battles in the Battle Palace, different natures allow the Pokémon to use different attacks or allow for them to change tactics when health is low - this does include the 5 'neutral' natures. In Sunyshore City the man that lives close to the Heritage Sites will ask to see Pokémon of an Naive Nature, Quirky Nature, and Serious Nature, once the player accomplishes this task they will receive 3 new Pokétch applications.
As of HeartGold and SoulSilver, all games after that have tinted the stats that are increased and decreased by a Nature. The stat that has become increased by 10% will be tinted in red, while the stat decreased by 10% will be tinted in blue.
|Nature||Stat +||Stat -||Poffin Favoured||Poffin Disliked|
|Careful||Sp. Defense||Sp. Attack||Bitter||Dry|
|Rash||Sp. Attack||Sp. Defense||Dry||Bitter|