I believe both C64 and DOS are betas shared by @QuarkTheAwesome a few pages back.I heard that RetroArch supports Material UI and XMB menu in Wii U [1.6.0 build]
Does it work? Also, new cores? Everyone is talking about C64 and DOS and I can't find it among these pages.
I might be wrong about C64, but check the latest nightly builds, the newest compiled cores should be there except for Dosbox.
And the other two menus do work (UI and XMB), simply be sure to get the assets package and put it in the correct directory.