Get the most ridiculous Miiverse posts and tape them all over the walls. I'm sure shoppers would love to see messages like...
"I'm so existed for this game""Say u love me""My mom peed on her self""I will **** a donkey now""Describe your vag*na" and various drawings of d!cks.
Have a bunch of people dress up as all of the Nintendo characters, including the bad guys like Bowser, Donkey Kong, etc. Then, have a fierce battle and fight with the person that's dressed as your enemy (Mario vs Bowser, Sonic vs Eggman).