Hey! I was wondering the same thing, but couldn't find much, other than a gfa packer that didn't run on my pc for some reason, switch toolbox, and some videos showcasing modded in levels. I've also started making a guide with all my findings and...
I played Yoshi's Woolly World with a friend once and had a great time with it (only 2 players total though), other than that I would recommend NSMBU or Super Mario 3D World because they have great co-op. NSMBU also has a huge mod called Cloudy...
The problem with X party blocked X bill that would have prevented X is that yes the bill probably would have worked great, buuuttt they put XYZDCBG in said bill as an attempt to sneak things in that tend to be completely unrelated to the original bills intent. It sucks because if they would just do a single thing they could probably get something done...