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Private Goomp is a Goomba who wears blue pajamas, and a minion of Bowser, introduced in Mario & Luigi: Bowser's Inside Story. However, he retroactively first appears as one of the first two Goombas and thus enemies that the Mario Bros. fight in Mario & Luigi: Superstar Saga, as revealed in the remake of the game.
Mario & Luigi: Bowser's Inside Story
In Mario & Luigi: Bowser's Inside Story, he is first seen with Corporal Paraplonk and Sergeant Guy trying to take back Bowser's Castle with a Banzai Bill Blaster. However, they don't have ammo, leaving their king to get some. When Bowser acquires a Banzai Bill, his three underlings fire it into the castle.
Later, Bowser runs into Private Goomp wandering around alone outside Tower of Yikk. In talking with Private Goomp, Bowser learns that one of the three Star Cures is stored in his Treasure Chamber beneath his own castle. Bowser hastily leaves for said Treasure Chamber without Private Goomp.
At the Treasure Chamber, Private Goomp returns with his former companions, watching as Bowser defeats the Fawful Express, and as Mario and Luigi repair Bowser's memory of the combination. Once he opens the safe, however, the three quickly push him inside, stating that Fawful bribed them with extra rations. This same safe is later found in Peach's Castle.
Private Goomp is later seen after the closing credits of the game. Private Goomp and his two companions visit Bowser, who is bedridden after a fight with the Mario bros. They apologize for their treason and ask to rejoin the Koopa Troop. Bowser pardons them along with the rest of his minions on the condition that they help with repairs on his Castle.
Mario & Luigi: Dream Team
In Mario & Luigi: Dream Team, it is revealed that Private Goomp was promoted along with his associates to "Bowser's Royal Guard", and now has a black hat with a Bowser emblem on it. He travels with Bowser to Pi'illo Island to find Princess Peach. Private Goomp also helps Kamek disguise as Princess Peach forming a lower section of the disguise. It is also shown that he and his associates dream of bossing around Kamek and Bowser one day. The trio are also fought in a boss battle as the Elite Trio.
After Private Goomp and his allies have been defeated, Kamek demotes them to janitors and sends them back to the castle. After Bowser is defeated, he, Kamek, Private Goomp, Sergeant Guy and Corporal Paraplonk decide to retreat. Although Bowser is mad that his plan failed and that it was Antasma's fault, he tells his three minions that they did pretty well by their usual standards, much to their joy.
Mario & Luigi: Superstar Saga + Bowser's Minions
Private Goomp appears in the side story mode Minion Quest of Mario & Luigi: Superstar Saga + Bowser's Minions with a larger role than the rest of his team. He initially attempts to blow off Captain Goomba's attempts at saving Bowser to do so himself. However, Fawful ended up brainwashing him with a gas, forcing them to fight. Private Goomp was ultimately defeated, but Fawful managed to steal away Bowser, also sending them flying. He and the rest of the trio also appeared and joined with the group. However, they were also responsible for setting up the Koopa Cruiser with a time bomb while Roy was fighting them under Fawful's orders as a fallback strategy in case Roy failed to beat them.
As with the others in the trio, he uses his Elite Trio garb, probably as a developer oversight.
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