10th October 2017, 4:44 AM
Use a flash drive. That won't require external power and there are a lot of pretty large capacity ones available these days. The Wii U's bigger design issue is the SD card slot is used exclusively for backwards compatibility with Wii software.
"On two occasions, I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question." ~ Charles Babbage (1791-1871)