To put a downloaded save onto a physical cartridge, you need a specialized dumper/flasher:
"One Cartridge, Every Creature: Technical, Ethical, and Cultural Perspectives on an All‑Pokémon Save File for Pokémon Emerald" pokemon emerald all pokemon save file
A distinction exists in the community between "legal" and "legitimate" Pokémon. To put a downloaded save onto a physical
The file naming convention is crucial. Rename the downloaded .sav file to match your ROM filename exactly. Every Creature: Technical
Place the downloaded .sav file into your phone's internal storage directory (usually located under Android/data/com.fastemulator.gba/files/save ). Ensure the filename matches your game ROM perfectly. Open My Boy! and launch the game. Moving the Save File to Real GBA Hardware