Alright, first you should know that wii flow cannot play GameCube games using itself you need to download a GameCube game loader program like devolution or dios mios (also Nintendont in the future will be available for full use just not now).
*IMPORTANT: ALTHOUGH THIS ALL WORKS AND SUCH WHEN USING THE WII U TO PLAY GAMES ON WII FLOW AND USING DEVOLUTION AS YOUR GC LOADER, WHEN YOU LAUNCH THE GAME FOR SOME REASON THE CONTROLLER MAPPINGS FOR ME ARE DIFFERENT AND I USE A GC CONTROLLER WITH MAYFLASH ADAPTER THAT CONNECTS TO MY WII MOTE TO PLAY GAMES ON THE WII U. I'M GOING TO TRY FINDING HOW TO FIX THIS OTHERWISE JUST WAIT FOR NINTENDONT TO COME OUT AND TRY THAT.
Make sure you keep the main game ISO file(s) under a /games folder (name it games not /games) on the root of you flash drive (the first things you see when you open up your flash drive contents through your computer). You can name the ISO files whatever you want really but it won't matter anyways because the name will be overwritten on your wii flow library of games when you download the game's cover and such.
If your using wii flow on a wii u (wii mode) the only GameCube loader that is compatible with it right now is devolution (and Nintendont In the future) in which you need to download its source file. Once you open that up you should see a data file I there with a loader.bin file that you need to place under the wii flow folder in the root of your flash drive. Just leave it In the folder not making a folder for it and it is not the wii flow folder under your apps folder.
For a normal wii you can use also use dios mios, (lite version for sd cards and the other one for flash drives) although I do not really have any experience with dios mios so if you want to use that for your normal wii then you will have to look somewhere else because I do not know to set it up with wii flow if it is even possible which it might not be.
To be safe do not make a folder for you games under the /games folder leave the ISO files as they are unless you feel like renaming them because if you try launching a GameCube using devolution by itself it can't read the games if you have them In a folder under the games folder.
Last thing is when wii flow is up and you flash drive is in your wii/wii u
try going to settings and set path then set GameCube games path, click the thing that looks like ... Then go back one then click your games folder again and click on the set option and that should reset path and make it notice that you have games in your flash drive. If you add anymore games on your flash drive then be sure to repeat this so it notices the changes you made. Also, make sure that in settings that game partition is set to USB since you're using a flash drive otherwise you would set it to SD for SD card users like me. You should also make sure that the default GC loader is devolution under wii flow settings. (
I wrote all this for questions that you or other people might have and want answered pretty much, but I made to sure to underline the main thing you want to try. For your problem)
For Wii U users when you click on a game before loading it up go to settings and turn GC memory emulator on since you can't put GC memory cards on the Wii U. You can do the same on a normal wii if you don;t want to use an actual GC memory card/don't have one and save data on the sd card/flash drive. You need to do this if you want to save data when playing a game. You need to do this for every GC game in your Wii Flow library.
Before launching Devolution on your Wii U (you WILL NEED a normal wii for this) you need to launch it on your normal wii first using 1 wii mote of your choice that you have (you will need to launch every game with the same wii mote for authentication/verification). i would use devolution by itself to be safe like i did and then you must put the disc of the game you're loading up in the wii for first time launch for verification. After this you won't need the disc to load the game up from your SD card/flash drive anymore and can load it up using the same wii mote on the Wii U.
My controller mapping that are changed: (only affects A,B,Y, and X; the mappings i concluded are from testing them out on super smash bros. melee and yes i have tried other game i have to see if the problem still occurs.)
A=Y
B=A
Y=B
X=Y
Also make sure that you flash drive is formatted to fat32. To do that you just right click the flash drive on your computer and click format, then set the options so that it is changed to fat32 format and leave allocation size to what it sets it to automatically as it doesn't really matter. Make sure though that you drag all contents of you flash drive temporarily to your computer before formatting as it will delete all things In the flash drive then just re-add the contents in after it is done.
I hope that helps!
