Slap Arena is a battle stage based on the story mode stage Slap Arena. Two ancient warriors, locked in eternal hitstop from hitting each other so hard, are displayed in the background. A lively crowd surrounds the arena, consisting of various humans, jennies, turnips, rubies, and even a titan and a hype snake.
The stage itself has a solid main platform with a dip in the center, and a platform going back and forth floating above the stage, similar to the Fancy Ruins platform. Walls lead down to the lower blastzone on each side, with a slight slope before the ledges. The two slopes leading to the lowered center area have spikes which jut out periodically. The spike duration roughly correlates with the position of the platform floating above—when the platform passes over the center, the spikes come out, and when the platform reaches the end of its path in a direction, the spikes recede.
- Added Slap Arena battle stage