If you want to run a 3DS emulator on Android legally, here are lawful alternatives:
The necessity of BIOS files can depend on the emulator you're using. For Citrus, the process might involve: 3ds Emulator Bios File Download For Android
: Will not load or show up in your library without these keys. If you want to run a 3DS emulator
Is there a that is giving you an error message? 3ds Emulator Bios File Download For Android