The main types of Viruses.
First Game Dr. Mario
Appearances Dr. Mario
Dr. Mario 64
Mario & Luigi: Superstar Saga
Mario & Luigi: Bowser's Inside Story
Mario & Luigi: Dream Team
Dr. Luigi
Attacks Charge
Defeated by Megavitamins
Any other attacks

Viruses are enemies that mainly appear in the Dr. Mario games. The Viruses main colors are Red, Blue, and Yellow and they can be only defeated by matching up three of the same colors.

Other Appearances

Mario & Luigi series

Mario & Luigi: Superstar Saga

Viruses are first seen in Mario & Luigi: Superstar Saga where they are only fought in Woohoo Hooniversity. In battle, they mainly attack by trying to bite either Mario or Luigi. If this attack isn't blocked back, the Virus may poison the brother. They are also defeated when all of the viruses in each battle is the same color. Viruses are seen briefly in Mario & Luigi: Bowser's Inside Story where they are one of the Toothy's attacks.

Mario & Luigi: Dream Team

Viruses are fairly common in Mario & Luigi: Dream Team where they are seen only in the areas when Mario and Luigi are searching for the five pieces of the Ultibed, but some appear in Wiggly's area. The Viruses always fight in groups and they attack mainly by charging at Mario and Luigi. They are defeated normally or by placing them in 3 same colors in a row.

Dr. Luigi

The Viruses are set to reappear in this game where they serve as the main enemies. Also, their designs have completely changed since their last appearances.