Swiggler

Swiggler is a large, Shroob-created, bio-mechanical Wiggler that was vital to the Shroob's conquest of the Mushroom Kingdom. Swiggler had the unique ability to transform the vim sucked from Toads into a fuel source for the Shroob's flying saucers. The giant Wiggler resided in a special room in the Vim Factory. In his lair, Swiggler would drink vim and use special chemicals inside its body, transforming the vim into fuel. Shroob UFOs would than attach themselves to Swiggler with special conducts, powering up the flying saucers.

During the events of Mario & Luigi: Partners in Time, Mario, Luigi, Baby Mario, and Baby Luigi confronted the massive Swiggler inside the Vim Factory. In battle, Swiggler could shoot poisonous clouds at the brothers (which could be countered with Hammer strikes, although some required two hits). Swiggler also had a glass of green Vim, which it would drink and power-up nearby Shroob UFOs. This allowed the flying saucers to shoot energy blasts at Mario and Luigi. Fortunately, the heroic brothers could Jump over these blasts to avoid damage. The left one would shoot at Mario and the right one would shoot at Luigi, however they could swap places and attack different brothers.

Attacking Swiggler proved relatively useless, as the monster had extremely high defense and would always counterattack the Mario quartet with several shockwaves immediately afterwards, forcing the heroes to jump to avoid them. This attack came in addition to Swiggler's regular attacks that came on its turn.

During the fight, Swiggler was aided by two Dr. Shroob guards. If one was destroyed, another Dr. Shroob would appear to take its place. The Dr. Shroobs behaved exactly as they always had prior to the quartet's encounter with Swiggler:they would use red and gray Shroob mushrooms to grow and shrink, respectively, attacking once they had assumed the new form. These Dr. Shroobs unintentionally aided in Swiggler's demise. This is because, by attacking them, the heroes could knock the Shroob mushrooms used by the Dr. Shroobs into Swiggler's Vim drink. If a gray Shroob mushroom was knocked in, Swiggler would grow sickly and be weakened upon drinking it, lowering its defense, and making it unable to attack. This presented a perfect opportunity for attack. Regardless, Swiggler would always return to normal after a few turns. On the other hand, if a red mushroom was knocked in, the solution would heal Swiggler significantly.

After the long battle, the Mario Bros. counterparts emerged victorious. The vim-transforming monster was destroyed, and a Cobalt Star shard was discovered. However, the victory ended as a partial loss. In the end, Baby Bowser arrived and stole the Cobalt Shard, escaping in his Koopa Clown Car to Yoshi's Island.

Trivia

 * Swiggler's name is a portmanteau of the word "Wiggler" and the word "swig," a small sip.
 * During the battle, the four Mario Bros. are awarded Experience Points and Coins for every Dr. Shroob that is defeated, meaning the player can delay the end of the fight to boost their coffers and maximize their EXP.