I don't believe Wi-Fi will work since the melonDS build included is very out of date. (BIOS/firmware shouldn't even be required if it was using the latest version!)
Side note as well: I heard that this app is breaking the open source licenses of some of the emulators included... Especially...
Ah, that's it then. You need to go into System Settings, TV settings, and change the connector type to non-HDMI in order for a picture to come out of the AV Multi Out connector, same as the Wii.
This reply might be silly, but are you going to the Wii U's settings to actually change the display output mode or are you just plugging in the cable and hoping it works?
hahahaha I'm half way through a bag off my Volcano and my tolerance is way down because I haven't been smoking much lately, so I was a little slow to catch that that was what your angle was