there is a PC Engine Emulator you can use on the DS called PCEAdvance but you need a slot 2 to run the emulator since it's designed for GBA. However to run games in it you need to use a tool called PCEA/PNES Builder(or you can use the builder that comes with PCEAdvance) to insert roms into the emulator .gba file, you will also need PCEToy32 to decrypt most USA roms since most of them are indeed encrypted and PCEAdavnced cannot read encrypted roms.

Here are the links:
PCEAdvance
PCEA/PNES Builder
PCEToy32