Pokémon statistics
Pokémon statistics determine how Pokémon fare in battle. There are six stats that are characteristic for each Pokémon: hit points (HP), attack, defense, special attack, special defense, and speed. Each of these is determined through hidden variables called base stats, individual values, and effort values, and all but HP are dependent on a personality value as well. The level of a Pokémon is the only variable that anyone can know while playing the game that influences stats.
Main Stats and Meanings
Hit Points: The overall health of a Pokémon. In the context of calculating statistics, this refers to the maximum HP, but in battle, a Pokémon taking attacks loses hit points. When that value reaches 0, the Pokémon faints and can no longer battle.
Attack and Special Attack: These stats determine the offensive power of a Pokémon with regard to physical attacks (attacks of type Normal, Fighting, Poison, Ground, Flying, Bug, Rock, Ghost or Steel) or special attacks (attacks of type Water, Fire, Grass, Electric, Ice, Psychic, Dragon, or Dark), respectively.
Defense and Special Defense: These stats determine the defensive power of a Pokémon, again with regard to physical and special attacks, respectively.
Speed: Determines which Pokémon attacks first in battle.
Special (First generation only): Statistics for special moves. Split in second generation.
Statistic Formulas
For attack, defense, special attack, special defense, and speed, the statistic is...
((2B+I+E/4)*L/100+5) * P
For hit points, the statistic is...
(2B+I+E/4) * L/100 + 10 + L
where...
B stands for base stat, a value unique for each species of Pokémon. Each Pokémon has a base stat for each of the six main stats, between 5 and 255. Shedinja's HP base stat is the only exception; it's HP is always "1" regardless of level, EVs or IVs.
I stands for individual value, a random integer between 0 and 31, inclusive. The individual values (IVs) for each stat are randomly determined when a Pokémon is encountered/captured. There is no way to know what they are without reverse calculation.
E stands for effort value. Effort values (EVs, also known as effort points or EPs) are gained when a Pokémon wins a battle (causes the opponent to faint). Each stat has a different EV. No stat's EV may exceed 255 and the total EVs over all stats may not exceed 510. Note that effort values are divided by 4 in the formulas. This value is also rounded down before the rest of the calculation proceeds. Each Pokémon battled grants effort points to any Pokémon that battled it when it faints, and these points are set for each species (a Beautifly will always grant 3 points for the special attack EV, and will do so for any of its opponents that spent a turn in battle with it). Any Pokémon in the wild automatically has 0 EVs in all stats, so it's possible to keep track of gained EVs through meticulous counting. In addition, EVs can be increased through the use of vitamins (HP Up, protein, iron, carbos, calcium, zinc, for HP, Attack, Defense, Speed, Sp.Atk and Sp.Def, respectively), but only the first 100 effort points can be gained through use of vitamins. (Each vitamin adds 10 points.)
L stands for level, the 2-100 integral value of each Pokémon that is visible to its trainer in the Pokémon games. Gaining a level depends on gaining experience points through battle.
P stands for personality value, which is .9, 1, or 1.1, depending on the nature of the Pokémon. Each nature boosts one stat's personality value at the expense of another (or boosts and lowers the same stat at once, ending at the neutral 1 for all stats). The effects of natures on personality values (PVs) are fixed for each nature (a "modest" nature will always boost the special attack PV to 1.1 at the expense of lowering the attack PV to .9, and so forth). For the RBY and GSC generations, the personality value is automatically 1, as natures were only introduced in Pokémon Ruby and Sapphire.
Note that for all of these stats, except for level, the values may (and probably will) differ between each of the main stats.
Contest Stats
In Pokémon contests, one phase of judging depends on the condition of the Pokémon in one of five attributes: beauty, coolness, smartness, toughness, and cuteness. These attributes can be increased in the following ways:
Pokeblocks: mixed using the berry blender in each contest hall. Different color Pokéblocks increase different conditions (although some Pokéblocks are "multicolored" and increase multiple conditions).
Scarves: giving certain colored scarves to a Pokémon increases the condition of a particular contest stat while the Pokémon wears it, using the same color system as Pokéblocks (there are only five kinds of scarves, though, one for each condition).
it:Statistica (Pokémon)