RetroArch - RetroArch is a frontend for emulators, game engines and media players.
melonDS - A Nintendo DS emulator with support for commercial games.
nds4droid - nds4droid is a free, open source Nintendo DS emulator written for Android smartphones.
Drastic - Drastic is a Android DS Emulator
iDeaS - iDeaS is a plugin-based Game Boy Advance and Nintendo DS emulator for Microsoft Windows and Linux...
No$GBA - If you have no money you can play Nintendo DS and Gameboy Advance game.