Gaia

Gaia, known as Gaiant (ガイアント) in Japan, are a family of viruses appearing in the games Mega Man Battle Network and Mega Man Battle Network 4. 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 Iron Body ability (greyed out in color, resembling iron); in Mega Man Battle Network, in this form they only take 1 HP damage from any attack, while in Mega Man Battle Network 4 they are completely invulnerable to attacks in their Iron Body state.

In Mega Man Battle Network, when attacking, Gaia will change color to that of their native variant and smash the ground with their hammer, upon which they release a three-square wide explosion traveling down one column at a time. If there is a hole panel in front of the virus, when it attacks, its hammer won't make contact with anything, successfully preventing them from executing their attack (similar to how GutsMan's shockwave attack works).

In Mega Man Battle Network 4, while attacking, they drop three stones from the sky (these panels are marked by shadows), instead of the shockwave attack as in the previous game. Gaia+ and their higher-ranked versions along with the rocks will crack panels at random, so maneuvering can be a bit hectic. Only when they change to their native color, during their attack process, that the player can properly 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 Iron Body)
Every variant of Gaia has this same look when not attacking.