Lavagon

Lavagon, known as Magma Dragon (マグマドラゴン) in Japan, is a virus from the Mega Man Battle Network series. The virus appears in and out of hole panels, warping around those panels and breathing fire at its target. They always appear on stages which have a total of 3 holes.

Lavagon
Lavagons are red dragon viruses that breathe red fire, which results in a homming panel lock-on. where a fire pillar rises from the ground, dealing damage; after the fire pillar dissapears, it leaves a fiery ring on that panel. They appear in the Apart Comp 3 from Kotobuki.

Bluegon
Bluegons, Blue Dragon (ブルードラゴン) in Japan, are blue dragon viruses that breathe blue fire which results in a homming panel lock-on, where a piece of ice projects from the ground, dealing damage and freeze the panel it hits. They appear in the last battle (#20) of the SS License test.

Yellowgon
Yellowgons, Yellow Dragon (イエロードラゴン) in Japan, are yellow dragon viruses that breathe yellow fire (electricity), which results in a homming panel lock-on, where lightning strikes from above, dealing the dmage. They appear in the last battle (#30) of the SSS License test.

Trivia

 * Since the variants of Lavagon, Bluegon and Yellowgon, only appear once each and after the completion of Mega Man Battle Network's main story, some people are not aware of their existance (as evident from various spriting sources, who claim that the two viruses are not present in the game, while their sprites are part of the code).