Tanoomba

Tanoombas are Tanooki-like Goombas found in both the Mushroom Kingdom and the Beanbean Kingdom. They resemble regular Goombas, except that the Tanoomba has raccoon ears, a raccoon tail, and a leaf on its forehead. Tanoombas have powerful mimicry abilities and are able to shapeshift into different objects and different creatures. However, Tanoombas can always be given away by the raccoon-like features or leaves that appear on their transformations.

''Mario & Luigi: Superstar Saga
During the events of Mario & Luigi: Superstar Saga, Tanoombas lived in an area north of Beanbean Castle Town. To attack, a Tanoomba will transform into a copy of Mario or Luigi (albeit a copy with a raccoon tail). After transforming, the Tanoomba will attack the brother who the shape-shifting Goomba didn't transform into (i.e. if a Tanoomba transforms into a Luigi clone, the Tanoomba will attack the real Mario). This attack can be countered with a Hammer strike. Additionally, a Tanoomba can attack by spinning its tail at a Mario brother. The brothers can jump to dodge this attack, but should be prepared to dodge multiple tail strikes. If Game Boy Horror SP is used, it will give out a Green Pepper when defeated.

''Mario & Luigi: Partners in Time
Tanoombas live on Thwomp Volcano in Mario & Luigi: Partners in Time. They use a variety of disguises. A Tanoomba can turn into a Toad (with a raccoon tail), a 100 Gold Coin (with the Tanoomba's face on it), a ? Block (with a leaf on top), or even a Thwack (with the Tanoomba's face on it). Once approached, the Tanoomba reveals itself and attacks.

In battle, the Tanoomba uses a variety of shape-shifting attacks (like their Beanbean counterparts, albeit different transformations). First, a Tanoomba can jump high and either turn into a Thwomp (with a raccoon tail) or an orange balloon (with a raccoon tail). If the Tanoomba turns into a Thwomp, it quickly falls and crushes a Mario brother. If the Tanoomba turns into a balloon, it falls slowly, causing damage when it hits a Mario Bro. Both of these attacks can be countered with a Hammer. Additionally, if a Tanoomba twirls when it jumps, it attacks Luigi. If it jumps without twirling, the Tanoomba attacks Mario.

A Tanoomba can also turn into a Spiny shell (again, with a raccoon tail). When it transforms into the shell, the Tanoomba slides into the Mario Bros., circling around and attempting to damage the brothers multiple times. This technique may even poison a Bro. To dodge this attack, Mario and Luigi have to jump as the Spiny shell approaches. Again, if the Tanoomba does a twirl jump before attacking, Luigi is the first brother to be attacked. If it hops normally, Mario is attacked first.

A stronger version of the Tanoomba that has been Shroobified, the Tashrooba, is found later in the game, at Shroob Castle.

Trivia

 * The name "Tanoomba" is a portmanteau of the words "Goomba" and "tanooki." The tanooki is a real raccoon-like creature that is often involved in Japanese mythology. Like the Tanoomba, the tanooki is a master of disguise and a shape-shifter. Additionally, the tanooki needs to use magical leaves to help it use its powers.
 * The leaf on the Tanoomba's forehead is a reference to the Super Leaf of Super Mario Bros. 3, which transforms Mario into Raccoon Mario. Additionally, the Tanooki Suit is another power-up available in the same game.
 * Tanooki-tailed Goombas that resemble Tanoombas appear in the Nintendo 3DS game, Super Mario 3D Land.