Dont have a Wii in hand, but used dolphin to check the cores and this is the info you need:
FB Alpha CPS1 -> 2.97.28
FB Alpha CPS2 -> 2.97.28
FB Alpha Arcade -> 2.97.29
FB Alpha NeoGeo -> 2.97.29
Mame2000 -> 0.37b5
With the version numbers, you just need the correct DAT files and TaDa!
That was tested with RetroArch 1.7.1 Stable.
Where can I get the .dat file for each core ?