Both players pick 5 different characters. Each character starts with 4 stocks, for a total of 20 stocks. They then pick their opening characters before the battle. They start on a random neutral stage, but they can agree on the opening stage.
When a player loses all of their character's stock, they pick another character and counter-pick a legal stage. Each player starts the battle with their remaining stock, and therefore self destructs to match their previous stocks from the last game. If a player loses their 20 stocks, they lose the match.
Win and get a coupon for TWICE the value of your purchase.