I don't think anything is going to be funnier than Charles Barkley vs. Michael Jordan, which is totally going to be allowed because there is absolutely no possible way that the Barkley: Shut Up And Jam Gaiden versions of these two can possibly be confused for the real people that they're based on.
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Nominate The Kid vs. The Guy (I Wanna Be The Guy) for the Greatest Gaming Rivalry Contest!
Also, nom Luigi/King Boo, not Luigi/Waluigi.