Goomba Tower

Goomba Towers, also known as Goomba Stacks, are Goombas stacked on top of each other (ranging anywhere from stacks of 2 to stacks of 10) that first appeared in Super Mario 3D Land.

Super Mario 3D Land
Goomba Towers attack by running at the player and attempting to hit him or her in a similar fashion to individual Goombas. Goomba Towers can be shortened or defeated depending on how many Goombas the stack has. For example, attacking jumping on a stack of 4 will reduce it to a stack of 3, and so on. Alternatively, they can be killed all at once with a Ground Pound or as Statue Mario in statue form. They can be defeated one-at-a-time by being jumped on, being hit with a fireball, or whacking them with Tanooki or Statue Mario's tail.

Two Goomba Towers are seen in Peach's Letters. One tries to attack her when she attemtps to escape, but she defeats it with her parasol. Another Goomba Tower is later seen chasing Peach with Bowser and his other minions. During the credits, Bowser is seen on top of a massive Goomba Tower, trying to reach Mario, who is carrying Peach home in his Tanooki form, but this ultimately fails.

New Super Mario Bros. 2
Goomba Towers reappear in New Super Mario Bros. 2, where they appeared to be stacked up even higher than before. The Goomba Towers can be defeated by the same methods as before. They can be affected by the Gold Ring, where they function the same as Gold Goombas, thus becoming a couple of Gold Goombas stacked together.

They first appear in World 1-1, where one three-stacked Goomba Tower appears before the Checkpoint Flag and one 8-stacked tower appears right before the Flagpole.

Super Mario 3D World
Goomba Towers once again return as common enemies in the game Super Mario 3D World. Once again, their attack pattern is simply to try to ram Mario or his allies; however, some Goomba Towers have a non-Goomba enemy, such as a Fire Bro, at the top. One Goomba Tower early in the game even has a Green Star in the middle of the stack and some Goomba Towers are sleeping. There are also a few that carry Super Mushrooms.

Mario Party 9
Goomba Towers appear in Mario Party 9 in the Goomba Spotting minigame, where players attempt to count the total number of Goombas that run across the screen as accurately as possible. Sometimes, Buzzy Beetles appear at the tower to trick the players into tallying them.

Mario Party: Island Tour
Goomba Towers appear in Mario Party: Island Tour. One Goomba Tower is the first boss of the Bowser's Tower mode (being faced off against on the fifth floor), and its boss minigame is Goomba Tower Takedown. Another appears in the board Perilous Palace Path, and determines whether the player takes the main path or the Bowser Zone.

Paper Mario: Sticker Star
In Paper Mario: Sticker Star, five Goombas appear in Bouquet Gardens and stack together as a Goomba Tower to bend into a wheel as part of their dramatic entrance to attack Mario and Kersti. The battle against them has Kersti demonstrate to Mario how the Battle Spinner works. Afterwards, the five Goombas are defeated in battle and subsequently surrender.

Mario Kart 8
Goomba Towers reappear in Mario Kart 8 as obstacles in Mario Circuit.

Captain Toad: Treasure Tracker
Goomba Towers return in Captain Toad: Treasure Tracker, acting the same as they did in Super Mario 3D World.

Mario Maker
Goomba Towers will reappear in Mario Maker. They are created when players stack multiple Goombas on top of each other when creating a level.

Trivia

 * In New Super Mario Bros. 2, if Mario or Luigi defeat a number of Goombas in the Goomba Tower and leaves the remaining Goomba(s) so they're offscreen, upon returning, the Goomba Tower will be renewed with its original number of Goombas.
 * When the Thunderbolt item is used on the Mario Circuit (Mario Kart 8) course, Goomba Towers fall apart. They then reform in a similar way to a Pokey, stacking up over the course of around a second.