There are extensions, and exceptions, and different licenses applicable, and fair use, and the concept of transformativeness, and... :)
Basically, IANAL, but if you just draw a picture of Mario, all you can do is hang it on your fridge. If you make it out of colored oatmeal, that may be enough of a transformative work for you to be able to sell and exhibit it. Or, say, a satirical cartoon for your newspaper featuring Mario, that might also be okay.
Probably not for anything commercial, not for any exhibitions or public viewing etc. You'd have to check the actual trademarks etc.