Introducing the Simple Stage (FFA)
The Simple Stage holds in its name its main feature, in that it's a stage with a single round composed of matches. Its main goal is to allow for Free-for-all matches, with a number of participants ranging from 2 to 4096 per match (if you are a Partner, else the upper limit is 256).
It was designed to accommodate the ever-growing Battle Royale mode, and is adaptable to any kind of free-for-all mode, from FPS Deathmatch to Racing , with Speedrun in between. While you may select a Simple Stage with a Duel match format, it was meant to be used with a Fixed Sets setting, and especially the Fixed Sets (Advanced) one, tailored for Battle Royale.