It's Not the Marioverse, it's the street fighter verse, Ryu can link more things (including NINTENDO and the so called mario verse) than any videogame character in the history of video games.
Ryu has fought SNK, ergo, the KOF and SNK multiverse is linked.
Ryu has fought Marvel, therefore he links marvel and everything Marvel has crossed over with.
Ryu has fought the cast of family guy and american dad.
Ryu was in both Tatsunoko vs capcom and Project X Zone, therefore he links absolutely every single anime series featured in every Super Robot Wars game ever, this includes stuff that aren't even mecha anime like idol M@ster, Miku, Godzilla and Little Witch academia as well as anything those series have crosed over with (like the Trigger multiverse)
Ryu was part of the Sonic and Megaman crossover, therefore he link a ton of sega properties.
Ryu has crossed over with the power rangers, and by extention anything the PR have crossed over with (including DC and the Ninja Turtles)
Guile was part of the Harvey Birdman game, ergo, Ryu links the entire Hanna Barbera multiverse.
Ryu fought the Tekken characters, so that makes him link the Tekken and Soul Calibur universe
Ryu is in smash bros.