If you want to continue working on Arduino, do that! You could consider making some things to help with the Showdown including:
A start/stop button that starts out with a red light lit. When you push a button, the light flashes three times (once per second) then turns green for "go."
A celebratory light/motor show to celebrate the winner of a battle.
Or, something else!
You don't have to build this, but it is a good place to start if you aren't sure how to build something from scratch.
You can use this to get an idea of how to build a circuit using a button and how to program your Arduino to have a button do something.