I think a big part of it is if the IP is the only marketable part of the “parody” and if it is parody at all. Is it a parody just because there’s jokes? If so, Pixar could make a Mario movie no problem.

But SNL can make a Mario sketch, because SNL isn’t called the Mario show and Mario isn’t featured in 100% of SNL promotional material. Same, Mario could appear in an episode of South Park or Family Guy, just not as a permanent replacement for Cartman