Dr. Shroob

Dr. Shroobs are yellow Shroobs that appear in Mario & Luigi: Partners in Time. They wear thick, swirly glasses. Dr. Shroobs are found in the Vim Factory, where they presumably monitored the factory's vim transformation process.

Battle
In battle, Dr. Shroobs attack with a ray gun, just like a regular Shroob. The energy blasts can be jumped over. Dr. Shroobs also use two items in battle: red Mushrooms and gray Mushrooms. The Dr. Shroob will hold its Mushroom out for a turn before using the item; if attacked while holding a mushroom, it drops the item.

The red Mushrooms make Dr. Shroob gigantic, while gray Mushrooms make Dr. Shroob tiny. After eating a Mushroom (regardless of color), the Dr. Shroob then attacks by charging into its opponent, inflicting more damage if big or less damage if small. Dr. Shroob's charge attack can be countered with a Hammer, unless it is small and Baby Mario/Luigi is on Mario/Luigi's back. During the boss fight against Swiggler, Dr. Shroobs put their mushrooms in the Swiggler's drink to make it stronger; red mushrooms heal Swiggler, and gray mushrooms weaken it, meaning that the Bros. must knock any red mushrooms they see out of their hands as soon as possible.

Trivia

 * During the battle with Swiggler, 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 coin amount and increase their experience levels.