I was so bored tonight that I just had to make this on flippin' MS Paint.
The characters and their counterparts are (in no particular order)....
Mario as Stan Marsh
Luigi as Kyle Broflovski
Wario as....Eric Cartman (I wonder why)
Waluigi as Kenny McCormick (Waluigi haters should like that)
Pikachu as Timmy (he can only say his name)
Sonic as Tweek Tweak (Tweek is a little hyper, Sonic is super fast...they kinda work out)
Yoshi as Butters Stotch (they both seem very friendly)
Kirby as Chef (I know Chef is kinda dead, but Kirby and Chef are both chefs, so whatever)
Solid Snake as Jimmy (don't ask me about this one)
Peach as Wendy (Stan and Wendy were kind of an item at one point, so I had no choice)
Snake/Jimmy kinda got ripped off because of my crappy printer. X(
BTW, if you don't like South Park or Mario (haha, just kidding about the Mario part) please don't come to the thread and say "South Park sucks". You can say that about the picture however, since it was done on MS paint.
South Park and the Nintendo/Konami/Sega characters are all copyrights of their respected owners (just in case any of them come to this site).