Anyone that is worried about the wii u auto updating if you have a old android device laying around setup the self host on that I use a old phone which has no service so my wii u has no chance to connect to the Internet.
This is what I do use a old android phone I had laying around used wifi tether for root has no chance to connect to Internet and self host through that work flawlessly.
I've had games that have froze at certain screens, for me personally I got the game working by switching the launching method for loadiine from Mii maker to smash bros and it worked after that.