Directional buttons

The directional buttons are the four blank, dark-gray buttons present on the left Joy-Con.

Overview
In normal gameplay, the directional buttons are the collective equivalent to the directional pad, which typically are to perform taunts. The up button performs up taunt, the left and right buttons perform side taunt, and the down button can perform down taunt. Pressing the left, up, and right buttons as a game is ending will also manually trigger its corresponding victory pose just like the D-pad.

When the left Joy-Con is used by itself and held horizontally, they change functionality to mirror the face buttons on the right Joy-Con. The up button becomes the B button and is used to jump. The right button becomes the Y button and also jumps. The down button becomes the X button and is used to attack. The left button becomes the A button, which performs special moves.

In Super Smash Bros. Ultimate, all four directional buttons can be remapped in the controls menu to perform other functions. Nintendo Switch hardware version 10.0.0 introduced the ability to map the functionality of any button to any other button from the console options menu, further diversifying how the directional buttons can be used in Ultimate.