From the Super Mario Wiki, the Mario encyclopedia
Spinning Slide is a special move performed by Super Bowser as the final attack to defeat a giant boss in Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.
When the HP bar of the boss is nearly depleted, it flashes yellow, and the menu only gives the option to use this attack. When it is used, the player must repeatedly tap the touch screen to make Bowser punch the boss repeatedly before uppercutting him into the air. As it falls, the player must then slide a clockwise circle on the touch screen to charge up a powerful punch to finish the boss off.
Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey