I Am Setsuna is a spiritual successor to Chrono Trigger to many. It's available on multiple platforms, but it's pretty clear that the Nintendo Switch is seen as the definitive version of the game with this new DLC.
The Temporal Battle Arena DLC is new party on party colosseum battle mode that will only be available on the Nintendo Switch version of the game. It pits players against monsters and other teams.
Available April 13, this DLC will be available through the Nintendo Switch eShop.