All Pokémon caught and owned in most games will have great variety in stats, even same species with the same nature and EVs. This is due to a factor called Individual Values, or IVs for short. Previous to Pokémon Diamond and Pearl, the only way to know a Pokémon's IVs was to consult with the IV Man in the Battle Frontier, and that was only in Pokémon Emerald. Plus, the IV Man would only tell the player the Pokémon's best IV and give a range of values it could possibly be, as well as a range of the overall IV total--all the Pokémon's IVs added up together. If a player wanted to know the exact IVs, the only place to go was online to an IV Calculator, and even an IV Calculator can't determine an exact IV if the Pokémon is at too low of a level.
Pokémon Diamond and Pearl, and later Platinum, introduced a new feature that can help the player further determine the IV of a Pokémon's best stat and at least let the player know if the best IV might be perfect: Characteristics. These characteristics tell the player the possible ones digit of the Pokémon's best IV. While only knowing the ones digit may not be helpful to determining an exact IV (unless the player has access to Pokémon Platinum and the Battle Tower's IV Judge), for competitive breeders, it can give them knowledge of whether they might have a perfect IV or not in a particular stat.
This page will provide a list of all the characteristics and the possible IV of that stat. Keep in mind that a Pokémon's characteristic always talks about their best IV, or one of their best IVs if they have multiple IVs that have the same highest value (ex. a Pokémon's Attack and Defense have an IV of 19). Characteristics that hint at a possible perfect IV will have an asterisk next to them for quick reference.
HP
- Loves to eat: 0 5 10 15 20 25 30
- Often dozes off: 1 6 11 16 21 26 31 *
- Often scatters things: 2 7 12 17 22 27
- Scatters things often: 3 8 13 18 23 28
- Likes to relax: 4 9 14 19 24 29
Attack
- Proud of its power: 0 5 10 15 20 25 30
- Likes to thrash about: 1 6 11 16 21 26 31 *
- A little quick tempered: 2 7 12 17 22 27
- Likes to fight: 3 8 13 18 23 28
- Quick tempered: 4 9 14 19 24 29
Defense
- Sturdy body: 0 5 10 15 20 25 30
- Capable of taking hits: 1 6 11 16 21 26 31 *
- Highly persistent: 2 7 12 17 22 27
- Good endurance: 3 8 13 18 23 28
- Good perseverance: 4 9 14 19 24 29
Special Attack
- Highly curious: 0 5 10 15 20 25 30
- Mischievous: 1 6 11 16 21 26 31 *
- Thoroughly cunning: 2 7 12 17 22 27
- Often lost in thought: 3 8 13 18 23 28
- Very finicky: 4 9 14 19 24 29
Special Defense
- Strong willed: 0 5 10 15 20 25 30
- Somewhat vain: 1 6 11 16 21 26 31 *
- Strongly defiant: 2 7 12 17 22 27
- Hates to lose: 3 8 13 18 23 28
- Somewhat stubborn: 4 9 14 19 24 29
Speed
- Likes to run: 0 5 10 15 20 25 30
- Alert to sounds: 1 6 11 16 21 26 31 *
- Impetuous and silly: 2 7 12 17 22 27
- Somewhat of a clown: 3 8 13 18 23 28
- Quick to flee: 4 9 14 19 24 29