RetroArch - RetroArch is a frontend for emulators, game engines and media players.
melonDS - A Nintendo DS emulator with support for commercial games.
MESS - Emulates most gaming systems that exist, emphasizing accuracy over speed.
Drastic - Drastic is a Android DS Emulator
No$GBA - If you have no money you can play Nintendo DS and Gameboy Advance game.
WinDS PRO - WinDS PRO contains the best emulators for the consoles Gameboy Advance and Nintendo DS for PC.