I don't have use for these much, but I tinker around sometimes in my spare time with my versions of a few shared universes. The general rule for them is that there is real time aging to the characters (rather than a sliding timeline) and to varying extents, everything licensed is included. So we have a Marvel that also includes a lot of Hasbro, Disney, Godzilla, etc., DC with various Warner properties, Image including TMNT, Power Rangers, and other Nickelodeon series (mostly because of TMNT), a Horrorverse, and a Smash-verse that ends up including most other video games.
There's a bunch of weird, screwy explanations for certain things fitting together, but mostly, I'm half-reapplying them to a less copyright-infringing OC universe of mine. But Spawn, the Ninja Turtles, and SpongeBob teaming up to take on Cthulhu and a Marvel team with the Kool-Aid Man, RoboCop, and Jem (from Jem & the Holograms, who I also made Hannah Montana's mom) are kind of funny.