Basically, every single TMNT thing. Including the comics, Including the shows, including the movies, including the Minecraft skins (literally shown as an alternate universe in one of the shows), including... the main Power Rangers universe, actually. Maybe including Stranger Things and Batman vs Teenage Mutant Ninja Turtles. Also, the DCAU has a multiverse crossover with the 2012 CGI Teenage Mutant Ninja Turtles show.
Boy, it'd be cool if they did that for the Crisis on Earth-203 fan comic. Anyway, that's a good example of fanfiction being "canonised", which I guess applies to Ghostbusters even though it's really silly.