Step 1: First, mod your 3ds. Then you can download TwilightMenu.

Step 2: Press Start+Power to open GM9. Then insert your game.

Press A on gamecart.

Click on the .nds file.

Press A on the highlighted text.

Repeat with .sav.

Finally, go to sd/gm9/out, and move .nds to sd/roms/nds (for .sav, move to nds/saves).

And, you’re done!