Nandbin Melonds ((full)) -
Also dump dsi_bios9.bin and dsi_bios7.bin from the same console. melonDS requires matching BIOS files for the NAND dump to work.
: Go to Config > Emu settings > DSi , link your NAND file, and set the console type to DSi . nandbin melonds
This is the only fully legal approach. You dump the NAND from your own DSi console. Also dump dsi_bios9