The Ground Pound is an ability that was first featured in the 2D game Super Mario Bros. 3 but mainly rose to prominenee in Super Mario 64. The move is usually executed by crouching in midair. If used correctly, your character will slam their bottom onto the ground. It can activate blocks and is usually more powerful than a regular jump.
In Super Mario 64 Edit
In this game, the Ground Pound can be used to activate Blue Coin Blocks, reducing damage taken from high falls, and most commonly defeating enemies. It is also used to make a quick landing with the Wing Cap.
It has to be used in levels like Behind Chain Chomp's Gate and Whomp's Fortress. In the former, Mario must ground pound the stump holding the Chain Chomp down while in the latter, Mario has to ground pound the Whomp King to defeat him.
In Super Mario Sunshine Edit
One of the main uses of the ground pound in this game is using it to flip Manholes, allowing Mario to access tunnels. It can also lead to Shine Sprites. The ground pound must be used to get the Shine Sprite at the lighthouse at Delfino Plaza and other locations.
Using the ground pound is key if you want to defeat certain bosses in the game like Petey Piranha and Wiggler. It also plays a major role in the final boss when Mario must ground pound parts of the slime-filled hot tub.
In Super Mario Galaxy and Super Mario Galaxy 2 Edit
In these two games, the ground pound is almost always used to activate large switches emblazoned with the "ground pound" symbol. Ground pounding them will make Star Bits or coins appear. Some enemies like Undergrunt Gunners can be defeated with the Ground Pound and stumps must sometimes be ground pounded to proceed into the next area.
The new Homing Ground Pound ability is activated by jumping, spinning in midair, and then using a ground pound to crash onto the ground.
In Super Mario 3D Land and Super Mario 3D World Edit
The ground pound isn't as widely used in these two games as it is in the previous four 3D Mario titles but it does maintain a strong presence.