GBA Overview

Gist: Particularities, key RNG concepts, and version differences of GBA games.

Particularities of GBA RNG Manipulation

In GBA games, the RNG advances every in-game video frame (every 1/60th of a second). This means RNG manipulation requires pressing A with a 1/60th second precision, making it more difficult than the DS generation. RNG manipulation for very rare traits can require waiting for a very long time (1h+ for each attempt). Fortunately, some advanced techniques exist to speed up RNG advances. vblanks can cause hard to predict RNG advances during the Pokémon generation, altering the outcome unexpectely. Those unexpected advances are the source of the differences between Methods 1-4. Still, they are good reasons to RNG manipulate in GBA games, most notably:

Only way to obtain all Ribbons on a Pokémon.
Only way to obtain Shiny Mew and Shiny Deoxys.

GBA RNG Mechanisms Overview

There is only 1 type of RNG for Pokémon generation. It is used to generate the PID (which dictates Nature, Ability, Shininess) and IVs. Shininess depends on PID, TID, and SID. This means you must know your SID to RNG manipulate a shiny Pokémon.

Key Differences between GBA Games

Game	Initial Seed	Useful For
Pokémon Emerald	Normally 0	Easiest to RNG Static, Wild, and Egg Pokémon
Ruby & Sapphire	With live battery: Random. With dead battery: Normally 5A0	Access to level 45 Groudon and Kyogre
FireRed & LeafGreen	Random	Only way to get Shiny Mewtwo and Unown Easiest way to get Shiny Articuno, Zapdos, Moltres

Console Interoperability

Pokémon can be traded between GBA and GameCube games. GameCube games are specifically useful for:

Only way to obtain Shiny Jirachi.
Obtaining Entei, Raikou, Suicune with rare traits is easier than on GBA games.

Pokémon can be transfered from GBA to DS games, but not the other way around.

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