Methods 1-4 in Emerald

Gist: What is a Method, the reason why Methods 1-4 exist, and how they impact Pokémon generation.

What is a Method

A method indicates how a Pokémon will be generated for a given RNG advance. RNG Advance + Method => Pokémon generation result A method is split into 2 components (ex: Wild-2):

Prefix: The program CPU instructions used to generate it. (ex: Wild).
Suffix: When the Vblanks occured (ex: 2).

Method Prefix: Program CPU Instructions

The program CPU instructions depends on how the Pokémon is encountered. For RNG manipulations, 3 of them are relevant:

Stationary Pokémon: Prefix is "Method" (Not convenient, I know...).
Wild Pokémon: Prefix is "Wild" or "H".
Egg Pokémon: Prefix is "Egg".

Program CPU instructions for Stationary Pokémon are the simplest. The GBA game generates PID then IVs, without additional RNG logic. Instructions for Wild Pokémon determine the encountered species from Encounter Table, apply Synchronize lead logic which can force multiple PID to be generated, then generate IVs. Instructions for Egg Pokémon select inherited stats from parents and more. This guide won't cover Egg generation in details.

Method Suffix: Vblank occurence

As explained in Understanding VBlanks, Vblanks can occur seemingly at any time, altering the Pokémon generation. How exactly the Pokémon generation will be affected depends if a Vblank occurs and on which program instruction exactly. This depends on many factors such as the map, background music, lead PID, the game played and how it is played (ex: via Pokémon Box Ruby & Sapphire).

List of Methods

Instructions	Methods	Rarity
Stationary	Method-1 Method-4	Very common Very rare
Wild	Wild-1 Wild-2 Wild-4	Rare Common Uncommon
Egg	Egg-Normal Egg-Split Egg-Alternate	Common Common Uncommon

Method-1 and Wild-1

Here's the game logic for generating a Pokémon:

Step	Advance At Step Start
Generate 1st half PID	1
Generate 2nd half PID	2
Generate Def, Atk, HP IVs	3
Generate SpD, SpA, Spe IVs	4

Method-1 and Wild-1 is when a Pokémon is generated and no vblanks occur. The Pokémon is generated using the value of the RNG of advances 1,2,3,4.

Wild-2

Wild-2 is when a vblank occurs between the steps "Generate 2nd half PID" and "Generate Def, Atk, HP IVs".

Step	Advance At Step Start
Generate 1st half PID	1
Generate 2nd half PID	2
VBLANK: Advance RNG	3
Generate Def, Atk, HP IVs	4
Generate SpD, SpA, Spe IVs	5

The Pokémon is generated using the value of the RNG of advances 1,2,4,5. The RNG value of advance 3 has no impact on the generated Pokémon.

Method-4 and Wild-4

Method-4 and Wild-4 are when a vblank occurs between the steps "Generate Def, Atk, HP IVs" and "Generate SpD, SpA, Spe IVs".

Step	Advance At Step Start
Generate 1st half PID	1
Generate 2nd half PID	2
Generate Def, Atk, HP IVs	3
VBLANK: Advance RNG	4
Generate SpD, SpA, Spe IVs	5

The Pokémon is generated using the value of the RNG of advances 1,2,3,5. The RNG value of advance 4 has no impact on the generated Pokémon.

Additional Methods

In theory, it is possible for Vblanks to occur between the steps "Generate 1st half PID" and "Generate 2nd half PID", which would result in Wild-3. However, because there are so few instructions in-between those steps, a Vblank very rarely occurs there. It is also theorically possible for Vblanks to occur during a very specific instruction in the RNG update, causing the RNG update to be skipped.

Learn more

Lead Impact on Wild Methods in Emerald: Understanding why the lead impacts which Wild method is triggered

Credits

RainingChain for the article.
Chinese translation: xuanyelin, Hakuhiro.