To play these fan-made NDS versions, you will typically need an NDS emulator such as SuperNDS for Android or a flashcart (like an R4) if playing on original hardware. Most ROMs come in .nds format and range in size depending on the amount of new content added.
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The dual-screen layout of the NDS is fully utilized for menus, battle commands, and the Pokédex. To play these fan-made NDS versions, you will