Passing here just to give the tip for those who want to use HD in retroarch and is in the formatting made by Wii u: ("storage_USB:/" formatted by wii u)
1 - All changes must be made by the retroarch, editing the .cfg file will not work
2 - I use SSD and it is very fast, even in USB mode
3 - I used FTPu Everywhere, it had 22 GB of games, it takes time, but it works. You can use fuse-wiiu, but as I use arch linux I couldn't use it so I used FTP
4 - Use version 1.8.9
5 - Change your playlist to the current version, you can convert using the
Marc Robledo website
6 - The only file I was unable to change and I don't think it is retroarch.cfg, which must be on the SD card
7 - If you use overlay, don't forget to manually change the .cfg files, and all other files that have no connection with retroarch.cfg
I think that's it, if anyone had more tips, put it there