For disc-based systems, you would look for sets from the Redump group. For cartridge games like the DS, No-Intro is the gold standard.
On the right-hand side of any Archive item page, a "Download Options" box lists available formats. Clicking "Show All" allows users to view the individual .nds files inside a collection. nintendo ds roms archiveorg
: A massive archive aiming to preserve thousands of titles from various regions, including North America (US), Europe (EU), and Japan (JP). Specialty Archives : For disc-based systems, you would look for sets