Emulators are great to get your project started and debugged. But always test your homebrew on a real nds while debugging. Not only the feel and look are different, colors, the experience of the touch with the stylus, the buttons, the sounds, also there can be some unexpected things behaving differently.
All emulators behave differently, some skip sound altogether, some give memory banks….
These are the two most usefull for me:
no$gba (only WINDOWS)
This emulator can be found here:
(What a sweet stroy this page is!)
NDeSmuME (also MACOS version, ships with the DEVKITPRO for MACOS)
This is the emulator which can show memory banks!
What about the sounds in the latest version?
Very usefull is checking these links once in a while looking for updates.
Downloading the emulators from other links can be a nuisance because of all kinds of pop ups or things attached probably caused by illegal downloading of nds games. Just things we never do. We make our own games, which is much more fun than playing games of others.