Pokémon data structure in Generation III

Pokémon in the, , and s are all stored the same way in a 100-byte structure. All numbers are stored in little-endian order.

Personality value
The personality value controls many things, including gender, 's letter, 's dots, any Pokémon's Nature, and more.

OT ID
The Original Trainer's ID number. This number is part of the XOR encryption key for the data section, and is also used in Shiny determination and the lottery. The least significant bytes of this number are the Trainer ID visible on the status screen.

Nickname
The Pokémon's nickname, limited to 10 characters. The characters represented by each byte are determined by the proprietary character set.

Language
The language of the game the Pokémon comes from. Eggs have this value set to. In international versions, the language value determines which character set is used when displaying the Pokémon's name and OT name. Any Pokémon with a language value of  will, in international versions, be named the game's regional variant of "EGG", ignoring the nickname field.

In Japanese versions, the language value is entirely disregarded. Names always use the nickname bytes decoded with the Japanese character set.

For Pokémon not in Eggs, the valid values are:

OT name
The name of the Pokémon's Original Trainer. The characters represented by each byte are determined by the proprietary character set.

Markings
The markings seen in the storage Box. These markings serve only to aid in organizing large collections of Pokémon.

Checksum
The checksum for the 48-byte data section of this structure. It is computed by adding all of the unencrypted values of that section one word at a time. If the computed sum and the stored checksum do not match, the Pokémon is interpreted as a Bad Egg.

????
Unknown, possibly simply padding (not used and usually set to either 0 or -1, depending on the data type).

Data
Certain data pertaining to the Pokémon that is stored in a special and encrypted format.

Status condition
The Pokémon's status condition is stored as follows:

The three sleep bits are used to indicate turns of sleep. So 1112 = 7 turns of sleep, 1012 = 5 turns, et cetera.

Pokérus
Not the same as the value found in the miscellaneous data substructure, which is a standard Pokérus byte. Instead, this value starts at 0xFF (and is in fact set to 0xFF initially even for Pokémon who haven't contracted Pokérus) and slowly ticks down. Cured Pokémon have this value set to 0.

Data location
A Trainer's party starts at the following addresses in the GBA's RAM. An opponent's party, or a wild Pokémon, starts at the following addresses.

The 600 bytes following these addresses describe a whole team of 6 Pokémon.

The full 100-byte structure for a Pokémon is only used to describe Pokémon being held in the player's party. When Pokémon are stored in the PC, their data is recorded using only the first 80 bytes of this structure, stopping after the data field. The last 20 bytes (excepting status condition) can all be recalculated from data in the data substructure when a Pokémon is withdrawn (level being derived from experience). This also explains why Pokémon suffering a status condition are "cured" when put in the PC.

This means there are also 33,600 bytes (80 bytes * 30 per Box * 14 Boxes) elsewhere in the GBA's RAM describing Pokémon in the PC. When the GBA's saved state (including memory contents) is unzipped into a 740,000+ byte file and viewed, the 14 Boxes of 420 Pokémon are stored in the general region of $038000 and $040000. In the US version of Pokémon Emerald, box data is between 0x02FE9888 and 0x02FF1BC8, non-inclusive. The first 6 80-byte structures make up, from left to right, the first row of Pokémon in box 1. The next Pokémon gets placed on the next row. After 5 rows (30 80-byte structures), the next Pokémon is placed in box 2, and so on.

Links

 * PokemonMakerV4x Help and 80 bytes Make a Pokémon