It looks like you're asking for a way to download a "Pokémon Sword and Shield GBA" version.
If you’ve seen a “GBA version” online, it’s almost certainly a or a demake — an unofficial game made by fans, not by Nintendo or Game Freak. Downloading and playing these typically requires emulators and ROM files, which often exist in a legal gray area (and may violate copyright laws, depending on where you live). Download Pokemon Sword Shield GBA
However, I should clarify that of Pokémon Sword or Shield exists. Those games were released exclusively for the Nintendo Switch . It looks like you're asking for a way
Classen Becker
chief Editor