Gaia

Gaia are a family of viruses appearing in Mega Man Battle Network and Mega Man Battle Network 4 games. When a match begins, Gaia viruses remain stationary and do not move throughout the progression of the battle. These virus are naturally equipped with the StoneBody ability (greyed out in color, resembling stone); in this form they only take 1HP damage from any attack. When attacking, Gaia will change color to that of their native variant and smash the ground with their hammer, releasing a panel-wide shockwave traveling down the row towards the player's area. These showckwaves leave the panels they traveled on as cracked panels. If there is a hole panel in front of the virus, when it attacks its hammer wont make contact with the anything, successfully preventing them from executting their attack (similar to how GutsMan's shockwave attack works). Also, it is only when they change to their native color, during their attack process, that the player can damage these viruses.

Gaia
Gaia have purple colored body with yellow decorations. They also bear a red hammer over their head.

GaiaEX
GaiaEX  have blue colored body with orange decorations. They also bear a pink hammer over their head.

Gaia2/Gaia+
Gaia2/Gaia+ have grey colored body with pink decorations. They also bear a yellow hammer over their head.

Gaia+EX
Gaia+EX have pink colored body with blue decorations. They also bear an orange hammer over their head.

Gaia3/GaiaMega
Gaia3/GaiaMega have yellow colored body with orange/pink decorations. They also bear a green hammer over their head.

GaiaMegaEX
GaiaMegaEX  have light-blue colored body with green decorations. They also bear a purple hammer over their head.

Gaia Prior to Attack (Using Stone Body)
Every variant of Gaia has this same look when not attacking.