• Play Rock, Paper, Scissors in pairs. Best 2 out of 3 wins.
• Each time someone loses, they and anyone in their cheering squad become part of the winner's cheering squad.
• Continue until there's a champion.

How do you maximize your chances of winning?

This is structured as a single-elimination tournament, except there's nothing to ensure that it's a proper binary tree. Because different games will take different amounts of time, and you're about 50-50 on winning each match, you want to play as few matches as possible while your opponents play as many as possible and eliminate each other. It's like a Slow Bicycle Race, where everyone has to keep making forward progress, but only just barely.

(You can also try to win by predicting your opponent's choices, but that's very hard. Unless your opponent is a small child in which case an "always choose paper" strategy can work well.)