Pokémon species data structure (Generation IV)
The Pokémon species data structure is a 44-byte structure that determines all information inherent to a Pokémon species, such as base stats, types, Egg Groups, and EV yield. Every Pokémon species in the Generation IV games has a data structure stored in the game's ROM.
Notes
Base Stats | ||
---|---|---|
type | offset | |
Base HP | byte | 0 |
Base Attack | byte | 1 |
Base Defense | byte | 2 |
Base Speed | byte | 3 |
Base Sp. Attack | byte | 4 |
Base Sp. Defense | byte | 5 |
Type 1 | byte | 6 |
Type 2 | byte | 7 |
Catch rate | byte | 8 |
Base Exp. yield | byte | 9 |
Effort yield | word | 10 |
Item 1 | word | 12 |
Item 2 | word | 14 |
Gender | byte | 16 |
Egg cycles | byte | 17 |
Base friendship | byte | 18 |
Level-up type | byte | 19 |
Egg Group 1 | byte | 20 |
Egg Group 2 | byte | 21 |
Ability 1 | byte | 22 |
Ability 2 | byte | 23 |
Safari Zone rate | byte | 24 |
Color | byte | 25 |
Padding* | word | 26 |
TM and HM flags | 13 bytes | 28 |
Padding* | 3 bytes | 41 |
Missing from this structure are moves known at Level 1, level-up moves, and evolutions, which are stored elsewhere.
Types
The types are associated with the following values:
|
|
|
If the Pokémon only has one type, both Type 1 and Type 2 will be set to the same value.
Effort yield
Each stat is assigned two bits to determine how many EVs the Pokémon will give in that stat. The last 4 bits in the byte are empty (0).
Bits | Stat |
---|---|
0-1 | HP |
2-3 | Attack |
4-5 | Defense |
6-7 | Speed |
8-9 | Special Attack |
10-11 | Special Defense |
Items
If an item is assigned to Item 1, the Pokémon will have a 50% chance of having that item when encountered in the wild. An item assigned to Item 2 will have a 5% chance of being held. If both Item 1 and Item 2 are the same, then the Pokémon will always be holding that item when it is encountered.
Gender
- Main article: Personality value → Gender
This value determines the chance that a Pokémon will be male or female. If the species is not all male, all female, or gender unknown, then this value is compared to the lowest byte of a Pokémon's personality value to determine its gender.
Value | Gender |
---|---|
0 | Always male ♂ |
1-253 | Mixed ♂ / ♀ |
254 | Always female ♀ |
255 | Gender unknown |
Level-up Type
The following values correspond to the different growth rates a Pokémon can have:
Value | Growth | Lv100 Exp |
---|---|---|
0 | Medium Fast | 1,000,000 |
1 | Erratic | 600,000 |
2 | Fluctuating | 1,640,000 |
3 | Medium Slow | 1,059,860 |
4 | Fast | 800,000 |
5 | Slow | 1,250,000 |
Egg Groups
The following values correspond to the different Egg Groups a Pokémon can belong to:
|
|
|
For Pokémon only in a single Egg Group, both entries are the same value.
Safari Zone rate
This value determines the rate at which the Pokémon will flee when encountered in the Safari Zone. Only Pokémon that appear in the Safari Zone have this value set.
Color
Color is used in the Pokémon Storage System box thumbnails. The following values correspond to the different possible colors:
|
|
For some Pokémon species, the bit 7 (the most significant bit) of this field is also 1. The reason for this is unclear.
TMs
The TMs which a Pokémon can learn are stored as a bunch of flags. Starting from the LSB of the first byte, and ending with the MSB of the last byte. The HMs are treated as TMs 93-100. The remaining 4 bits in the last byte are all 0.
Fingerprint
Below is a sample of the data for the first Pokémon species data structures.
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // ?????????? (used for unknown/glitch Pokémon) 2D 31 31 2D 41 41 0C 03 2D 40 00 01 00 00 00 00 1F 14 46 03 01 07 41 00 00 03 00 00 20 07 35 84 08 1E 10 02 20 24 66 92 02 00 00 00 // BULBASAUR 3C 3E 3F 3C 50 50 0C 03 2D 8D 00 05 00 00 00 00 1F 14 46 03 01 07 41 00 00 03 00 00 20 07 35 84 08 1E 10 02 20 24 66 92 02 00 00 00 // IVYSAUR 50 52 53 50 64 64 0C 03 2D D0 00 06 00 00 00 00 1F 14 46 03 01 07 41 00 00 03 00 00 30 47 35 86 08 1E 10 02 28 24 66 92 0A 00 00 00 // VENUSAUR 27 34 2B 41 3C 32 0A 0A 2D 41 40 00 00 00 00 00 1F 14 46 03 01 0E 42 00 00 00 00 00 23 06 51 CC E4 1E 82 12 01 A4 46 92 02 00 00 00 // CHARMANDER 3A 40 3A 50 50 41 0A 0A 2D 8E 40 01 00 00 00 00 1F 14 46 03 01 0E 42 00 00 00 00 00 23 06 51 CC E4 1E 82 12 01 A4 46 92 02 00 00 00 // CHARMELEON 4E 54 4E 64 6D 55 0A 02 2D D1 00 03 00 00 00 00 1F 14 46 03 01 0E 42 00 00 00 00 00 33 46 71 CE E4 5E 8E 16 09 A4 46 B2 02 00 00 00 // CHARIZARD 2C 30 41 2B 32 40 0B 0B 2D 42 10 00 00 00 00 00 1F 14 46 03 01 02 43 00 00 01 00 00 65 32 53 CC 40 1E C0 02 00 22 46 C2 07 00 00 00 // SQUIRTLE 3B 3F 50 3A 41 50 0B 0B 2D 8F 10 04 00 00 00 00 1F 14 46 03 01 02 43 00 00 01 00 00 65 32 53 CC 40 1E C0 02 00 22 46 C2 07 00 00 00 // WARTORTLE 4F 53 64 4E 55 69 0B 0B 2D D2 00 0C 00 00 00 00 1F 14 46 03 01 02 43 00 00 01 00 00 75 72 53 CE 40 1E C8 02 88 A2 46 C6 0F 00 00 00 // BLASTOISE ...
|
![]() |
This data structure article is part of Project Games, a Bulbapedia project that aims to write comprehensive articles on the Pokémon games. |