I have been busy with... things.
Shared Crossover Universes are all very different in origin, but usually, they're more Superhero-y or Anime-y then anything, with a spare few (like Krimzonverse) having different origins.
Guardian-Verse stars Wolfblade, for instance, who is just a regular dude in wolf armor that wields a sword, but features very 'power-wanky' Saiyans, a lot of (maybe slightly bigoted) 'fixing' of modern installments of new things, and a fanchild between Wolfblade and his love interest, Daisy Johnson from Agents of SHIELD...
Vice-Verse is hard to discern much of anything from, but it's known for some pretty overpowered takes on established characters. Vice is the lead character, who is a Sonic OC, but is also something called 'Truth', which may be more overpowered then most 2000s fanfiction author's OCs... Also, it takes place in a post-apocalyptic world, and it's assumed Truth did the Apocalypse here.
Krimzonverse is a reboot of the previously-mentioned on the board Crossover Chaos, put forth in the SCU style. Probably one of the better ones here, even if Elaine (Joe Kido) is written rather 'trans woman chaser'-y still. I find the concept of an SCU using stuff other then DBZ and comic books to be fantastic, but I think the wacky execution of this SCU makes it suffer at least a little bit.
I don't know too much about practically any of the others, as I am currently doing research on ones that aren't these ones, that don't post facts frequently.
I also note that the SCU currently has a villain from one I don't know too much about, the Crossverse, menacing these ones above, among other ones I don't know too much about.