If you are experimenting with multiplayer or different regions, newer versions of melonDS (like 1.0 RC) use a .toml configuration file. This allows you to manage separate NAND files for different instances, though setting unique NANDs for every player in local multiplayer can still be a bit tricky.
For a step-by-step walkthrough, the following community resources are highly regarded: DSi Emulation on melonDS - A Step by Step Guide (Reddit) nand.bin melonds
When you see a file named nand.bin in the context of melonDS, it is a bit-for-bit dump of that internal memory. It is the "soul" of a specific Nintendo DSi console. If you are experimenting with multiplayer or different
: Emulation aims for accuracy. By requiring a nand.bin dump from a physical console, melonDS ensures that the software environment matches the original hardware's constraints, including read/write speeds and storage limits. Technical Challenges: From Physical to Digital It is the "soul" of a specific Nintendo DSi console
The only legal way is to using custom firmware (like Unlaunch + dumpNAND). You cannot download it from websites — that’s piracy and against emulator policies.