What do you mean? Are they garbled... or do you just don't like the graphics?
Well, you have to keep in mind that they are only GameCube games, not Wii games, so of course graphics probably won't be as good as Wii games...
And installing both the Wiigator and waninkoko cMIOS will be pointless, as they overwrite each other, meaning the last one you installed will be the one you have. Did you install the waninkoko cMIOS last?
Are you trying to play in progressive 480p graphics mode?
If so...
I know that PAL GC games do not have 480p mode in them at all (only 50hz and PAL60hz).
As for NTSC games, I'm not sure if they all can support 480p, but I know that some can.
...maybe try installing the Wiigator cMIOS (not the waninkoko one), and try to use it to force the video mode you want?
