OK, here is the method you can use to play get wiimmfi to work on your wii u's wii mode or your regular wii. This is the exact method I used, so I can say that it does work. (however i can't guarantee that you won't run into your own problems.. so be cautious if you get stuck)
The first few steps are about getting Homebrew Channel using Smash Brawl. Skip ahead if you already have Homebrew you can skip to step 8. if you want to install homebrew by a method that does not use Smash, see the links at the very bottom and then return to step 8.
1. You need the following: a REGULAR SD card.. not SDHC, SDXC, or otherwise. This one works
https://www.amazon.com/Sandisk-2GB-SD-Card-SDSDB-2048-A11/dp/B000WHFMR2/ref=sr_1_12?s=pc&ie=UTF8&qid=1479401609&sr=1-12&keywords=sandisk+sd+card&refinements=p_n_feature_two_browse-bin%3A6518302011you also need a copy of Super Smash Bros Brawl. you must go into Brawl and delete all the stages in the Stage Creator section, even the ones that are demos.. there can't be any stages there of any kind.
2. Next you need to use the piece that will actually start-up the Homebrew channel in the game.. that is referred to as an exploit, and it is called Smashstack. Extract the contents to the root of your SD card (i.e. your SD card should be completely blank and these extracts go right on the SD card, not in any additional folders or anything like that) link - wiiubrew.org/w/images/4/4e/Smashstack.zip
3.*PAL/NTSC-K users must follow these additional steps in this guide:web.archive.org/web/2014032622…zzl.org/smashStackPK.html (dislaimer, i don't know anything about this... its just something I was told but since I'm not PAL i've never done it)
4. There are two more files you need to install HBC. i don't really know how these work to be honest but they are part of the installation process. Place these on the root of your SD card just like you did with Smashstack. links - mediafire.com/download/07mj83x8h0w0f0c/bootmini.elf and mediafire.com/download/v3rhddr6cst34h5/boot(3).elf rename that second one to "boot.elf" after you download it
5. Assuming you already deleted all the stages out of the Stage builder in SSBB, insert your SD card, then launch the game and go to the Stage Builder.
6. The installer should launch automatically if you have done everything correctly. follow the prompts and tell it to install the Homebrew channel
7.once it is installed it will take you to the homebrew channel. you'll notice there is nothing there, just water. press the home button on your remote to get out of there. remove your SD card and delete all the contents from it. You don't need those things anymore and you don't want them on your SD card because they could interact with other things if left there
8. Next you just need to put the Wiimmfi patcher on your SD card and thats it! It should go on the root like the ones you did from before. now, insert the SD card back in your wii/wii u and you should see the wiimmfi patcher when open Homebrew channel. when you want to play a game that uses wiimmfi, you have to put the game in, then go to homebrew channel and launch wiimmfi. do this everytime you want to play online. link - chadsoft.co.uk/downloads/autowiimmfipatcher0.4.zip
9. Thats it! please note that this is the process for disc-based games. If you want to play WiiWare games online there are a few extra steps. I can show you those too if you want.
Now, if you skipped down here because you don't want to use Smash Brawl, the first thing I can say is that I haven't done any of these options. But here they are:
for getting homebrew on wii mode of wii u without a game at all:
https://gbatemp.net/threads/wuphax-hacking-vwii-with-iosuhax.446786/for getting homebrew on regular wii with games other than Smash (notice that the other games have some limitations in terms of the firmware version on your wii..also I"M NOT SURE THAT THE OTHER ONES WORK ON WII U OR NOT.. that would be risky I think) -
http://wiibrew.org/wiki/Homebrew_setupplenty of youtube videos on this topic, search there if interested.
lastly, a guide that talks about Wii u wii mode hacking and explains some terms.. it also has a lot of this same stuff on there, could be fun to look thru this if you find it interesting -
https://gbatemp.net/threads/the-definitive-vwii-hacking-guide.425852/if you make it thru all of that.. AND you did it on a wii U... and you usually play wii mode in 16:9... you notice that the homebrew plays in 4:3, forcing your wiimmfi games into 4:3. if you want 16:9 i can help fix it =)
lastly i can say that it is possible to find other info on Wiimmfi thru google searches.. there is other stuff out there but its mostly spread thru different forums and stuff like that and I have lost some of those links.. you could try searching for stuff if you're interested but everything you need is here, up until you get to WiiWare games (if you even want those).
Hope this helps! let me know if you have any questions..