Proponents of ROM packs often argue that games no longer sold by Nintendo constitute "abandonware." However, legally, copyright persists for decades after publication, and Nintendo’s active enforcement of its IP portfolio invalidates the claim that these works have been abandoned in a legal sense.
First, I should mention that sharing or downloading ROMs for commercial games is against the law if you don't own the original copy. It's important to uphold the rules here. Then, maybe suggest legal ways to get DS games, like purchasing physical copies or using emulators with your own purchases. Some platforms have digital versions, but Nintendo DS games aren't available on their eShop anymore, so that might not be an option.