Pokémon 3rd Generation

This is a work in progress by Kawa. The content is being kept on this page to later be split and standardized.

The third generation Pokémon games are comprised of Ruby, Sapphire, Emerald, FireRed and LeafGreen. Since all five share a common set of data structures with only some offsets and minor details in difference, it seems more effective to consider them one single "game" and note the differences where applicable.

Notable ROM data offsets

Description		FR	R	Notes
Battle sprites		$2350AC	$1E8354	Pointer tables are in system order.
Monster heights		$235E6C	Unknown	N/A
Battle back sprites		$23654C	$1E97F4	Pointer tables are in system order.
Battle sprite palettes		$23730C	$1EA5b4	N/A
Battle sprite shiny palettes		$2380CC	$1EB374	N/A
Trainer sprites		$23957C	$1EC53C	Offset is a pointer table.
Trainer palettes		$239A1C	$1EC7D4	N/A
Trainer Class names		$23E558	$1F0208	N/A
Trainer data		$23EAF1	$1F0525	N/A
Pokémon Species names		$245EE0	$1F7184	Names are listed in system order.
Move names		$247094	$1F8320	N/A
Ability names		$24FC4D	$1FA26D
Move data		$250C04	$1FB12C	Data is stored in the same order as the move names.
TM allowance sets		$252BC8	$1FD0F0	N/A
Pokémon base stats		$254784	$1FEC30	Stats are listed in system order.
Move sets		$257496	$20192A	N/A
Evolution chains		$25977C	$203B90	N/A
Pokémon Party/box sprites		$3D37A0	$3BBD20	Offset points to a pointer table. Data is in system order.
Party icon palette		$3D3740	$E966D8	N/A
Party icon palette LUT		$3D3E80	$3BC400	Simple byte array
Item data		$3DB028	$3C5580	N/A
TM-to-Move table		$45A5A4	$376504	Maps TM numbers to moves
Pokédex data		$44E850	$3B1874	Pokédex data is in National Dex order.
Footprints		$43FAB0	$3B4EE4	Offset points to a pointer table
Contest data		N/A	$3C9408	N/A
Cries		$48C914	$452590	M4A Voice Group-style pointer list. In system order?

Following the Pokémon image pointers, you may notice that each species has all its image data in one chunk.

More information on the data structures can be found at Bulbapedia: Category:Structures

Images

Trainer and monster images are LZ77-compressed 64 by 64 pixels, 16 colors. Trainers' back-facing images are much taller and (in FireRed/LeafGreen) uncompressed. Monster front images in Emerald are 128 pixels tall to allow animation. In all games, certain monsters always have nonstandard heights (i.e. Castform). Alternate colors (aka shiny) are usually represented by the back-facing images since it makes an intuitive kind of sense.

Maps

Maps are split among banks, each bank roughly being one location. For example, there is a bank with all the cities and routes and several banks with each city's interiors. Generally, a map can be defined by a Doom-like "bank X, map Y" scheme. In FireRed, the bank pointer list is at $3526A8. Following one of the pointers found there yields that bank's map pointer list, which can be followed to a given map's header. Here is the map header format, including example data from Pallet Town (B3M0, 0x350618):

Data type	Description	Example
Pointer	Map data	0x082DD4C0
Pointer	Event data	0x083B4E50
Pointer	Map scripts	0x0816545A
Pointer	Connections	0x0835276C
Short	Music index	0x012C (Pallet Town)
Short	Map pointer index?	0x004E
Byte	Label index	0x58 ("Pallet Town")
Byte	Something with Flash?	0x00
Byte	Weather	0x02
Byte	Type	0x01
Short	???	0x0601
Byte	Show label on entry	0
Byte	Battle type?	0

The map layout data is another header:

Data type	Description	Example
Long	Width in tiles	24
Long	Height in tiles	20
Pointer	Border	0x082DD0F8
Pointer	Actual map data	0x082D1D00
Pointer	Global tileset	0x082D4A94 (outside)
Pointer	Local tileset	0x082D4AAC
Byte	Border width	2
Byte	Border height	2

Border size is only in FireRed/LeafGreen. In R/S/E it is missing and borders are always 2x2 squares.

Map data is quite straightforward: each 16-bit entry encodes the tile number and attribute. The trick is that there are only 64 attributes and 512 tiles, so the 16-bit entry is split up 7:9 instead of 8:8. The border data is technically the same format, but does not use attributes^{[check this]}.

Important Notice: The above statement is not accurate, at least not for Ruby. Tiles and attributes are broken up 6:10, not 7:9. For example, a map tile in Advance Map that shows as "block 1D4" with a movement permission of "01" will be represented in a hex editor as "D405", which is "1101 0100 0000 0101" in binary. To extract the tile you take the last 2 bits "01" and prepend that to the first 8 bits. This gives you "01 1101 0100", which is "1D4". Bits 9-14 are "000001" which gives a hex value of "1". - Joncom

Kawa is now left to ponder what to add next.