Dr. Shroob

Dr. Shroobs are yellow Shroobs that wear thick, swirly glasses that appear in Mario & Luigi: Partners in Time. During the Shroob invasion of the Mushroom Kingdom, Dr. Shroobs were stationed in the Vim Factory, allowing them to monitor the factory's vim transformation process.

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 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. Additionally, a Dr. Shroob holds its Mushroom for a turn before using the item. As such, if a Dr. Shroob is attacked while holding a mushroom, it drops the item. When fighting with the Swiggler, Dr. Shroobs put mushrooms in the Swiggler's drink to make it stronger.

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 coffers and increase their experiences levels, they also change the solution, red mushrooms heal Swiggler, and gray mushrooms weaken him.
 * You don't have to destroy them in the battle with Swiggler, to win the battle.