I've gotten Paper Mario working with no issues. Just make sure to enable "force 4:3" if you haven't. Though that should lead to visual glitches, not failure to launch. Try getting the Paper Mario and Metroid Prime isos from a different source, as nintendont is more picky about isos than dolphin. The most likely culprit is the isos you're using. Try ripping them directly from your copy or downloading them from a different source. I've been able to get all the wii games I've tried working (granted, this is just a small handful of titles), so the issue likely lies with something on your end.