no$gba worked fairly well and strangely enough can emulate 12 (!) consoles at once. I have no idea what the purpose of this is, but I'm hoping you could emulate 4 consoles and wire them together with an emulated link cable for split screen mario kart. I'll probably invite a couple of friends over later this week and try it.
My friend told me that desmume didn't work for him when he tried it out months ago but we tried again today and it worked very well.
That's leaving JPCSP left to test, hopefully it works.