Pokémon Evolution data structure (Generation III)

Data on the evolution of Pokémon is stored as a series of 6-byte structures in Generation III. These structures must be aligned on a 4-byte boundary, and each Pokémon species has 5 such entries, for a total of 40 bytes per species.

In all Generation III games, evolution data is situated between the Pokémon move list data pool and the actual Pokémon move list index; see Move list data structures in Generation III for a list of locations.

Pokémon Evolution Data Structure

Each species has 5 substructures, as Eevee has 5 evolution options. The overall structure is laid out as follows:

Offset	Size	Type	Notes
0x00	6	Substructure	First Substructure
0x06	2	Padding due to alignment
0x08	6	Substructure	Second Substructure
0x0E	2	Padding due to alignment
0x10	6	Substructure	Third Substructure
0x16	2	Padding due to alignment
0x18	6	Substructure	Fourth Substructure
0x1E	2	Padding due to alignment
0x20	6	Substructure	Fifth Substructure
0x26	2	Padding due to alignment

Pokémon Evolution Data Substructure

The 6-byte substructure is organized as follows:

Offset	Size	Type	Notes
0x00	2	uint16_t	Method of evolution - How this Pokémon will evolve. This can be one of the following values: 0x0001 - Evolves by happiness without regards to time of day 0x0002 - Evolves by happiness during the day 0x0003 - Evolves by happiness at night 0x0004 - Evolves by level up 0x0005 - Evolves by trade without items 0x0006 - Evolves by using an item on the Pokémon 0x0007 - Evolves by trading the Pokémon while holding an item 0x0008 - Evolves by level up, but only when Attack is greater than Defense 0x0009 - Evolves by level up, but only when Attack is equal to Defense 0x000A - Evolves by level up, but only when Attack is lower than Defense 0x000B - Evolves by level up, but only when the personality value permits (Wurmple → Silcoon evolution) 0x000C - Evolves by level up, but only when the personality value permits (Wurmple → Cascoon evolution) 0x000D - Evolves by level up, but may spawn another Pokémon if permitted (Nincada → Ninjask evolution) 0x000E - Evolves by level up, but is only spawned if the conditions permit (Nincada → Shedinja evolution) 0x000F - Evolves by beauty
0x02	2	uint16_t	Parameter - The meaning of this is dependent on the method of evolution - the item, the level, etc. Not used and zeroed out where applicable. Note that the parameter is used for the beauty threshold, but is not used for happiness thresholds.
0x04	2	uint16_t	Target Pokémon - The Pokémon which this Pokémon will evolve to. See List of Pokémon by index number (Generation III) for a list of values.

All unused entries will be entirely zeroed-out.