This is a mini-game i created called island boxing

Step 1: Body of Water

Find a reasonably large body of water to make the mini game

Step 2: Rectangle

Build a large rectangle in the water out of a block of your choice

Add 3 blocks on each side of red and yellow although it doesn't really matter. Make sure the team blocks are a different colour than the middle

Get some friends to play with. You can only play with two people at a time but you could do a mini tournament.

Each player starts at their end when the referee says go they both start punching each other. The person to fall into the water wins.

Alternatively you could do it on land and around it put lava to spice it up a bit.