Andromeda

Andromeda is a war--engine capable of destroying planets. The FM-ians mention it during their raids on Earth, and apparently, Omega-Xis has something they need to activate it- the Andromeda Key. Ophiuca states that it needs two things: the Key and the FM King's control panel. When Omega-Xis leaves Stelar|Geo], the revived FM-ians ambush him and, despite LyraNote's attempt to help, succeed in taking the Andromeda Key. Apparently, they plan to have Andromeda consume all life and destroy planet Earth, just like it destroyed Planet AM. They start kidnapping people to feed them to Andromeda, but are thwarted by MegaMan and the Satellite Admins.

Video Game
Later on in MegaMan Star Force in the Space Station Peace, after MegaMan deletes all the FM-ian warriors and confronts the FM King, Cepheus, the FM King summons Andromeda. It is a huge monster with a big mouth and large teeth. Omega-Xis states that it has an EM body, but all it ever does is eat other EM beings. Half-way through the battle, it transforms into a robotic, more humanoid form. After MegaMan defeats Andromeda, Cepheus sends it for another go at MegaMan, and Geo can't fight anymore because of the King's strong Z-waves. However, it goes cannibalistic and tries to eat Cepheus, but Geo is still helpless. Geo then remembers his friends who are depending on him, and his father, and that gives him strength again. Using one powerfully charged shot, he destroys Andromeda once and for all, saving Cepheus and planet Earth. Geo and Omega-Xis both forgive Cepheus.

Anime
Andromeda has a similar role in the anime. FM-ians constantly attack Earth in search of the Andromeda Key, which is in the possession of Omega-Xis. When Omega-Xis comes back to help Geo, they battle against the FM-ians but are overpowered, and CygnusWing captures Omega-Xis and obtains the key. The Satellite Admins LeoKingdom, PegasusMagic, and DragonSky, then stop the fighting and explain to Geo he true nature of Andromeda: a machine designed to destroy planets that once destroyed Planet AM, the home planet of the Admins. They grant him the Star Force to help destroy Andromeda, and they also save Omega-Xis from the FM-ians. While MegaMan battles the FM-ians, the GeminiSpark twins appear and attempt to steal the Key from CygnusWing. After MegaMan destroys Cygnus, CancerBubble obtains the remains of the Key.

The FM-ians now have a new goal: to gather enough Negative Energy from humans to revive Andromeda. During a mass attack on the city, the Key is destroyed, and the FM King Cepheus orders his warriors back to Planet FM, deciding to end the war. GeminiSpark, however, is not content. He murders and erases all his fellow FM-ians since they yield more Negative Energy than humans, revealing that the Key CancerBubble had was a fake. Despite failing to delete LyraNote and CancerBubble, they proceed to revive Andromeda, which was hidden in an iceburg all along, with the Negative Energy they already have. Andromeda then rises and heads for Echo Ridge, but MegaMan and LyraNote try to intervene. They are, however, quickly overpowered, and are both thrown unconscious into the ocean, only to be saved by CancerBubble. Since LyraNote took the full hit for MegaMan, she remains unconscious, while MegaMan confronts Andromeda alone. Even though he uses the Star Force, he couldn’t even damage it, and when he freezes it, it transforms to its robot form and knocks him unconscious on the street, revealing his identity to his friends. The Satellite Admins use the remaining power of the Star Force to destroy Andromeda, sacrificing themselves in the process. MegaMan then finishes Andromeda off. However, it doesn’t end, as GeminiSparkWhite betrays his other half, GeminiSparkBlack, to fully restore the Key and revive Andromeda. Andromeda then digs towards the Earth’s core to blow it up, and GeminiSpark leaves for outer space. MegaMan follows and catches him, but he throws the key towards Earth. MegaMan dives and destroys the key just in time, stopping Andromeda, while Cepheus deletes Gemini and apologizes to Earth and to Omega-Xis.

Arsenal
Andromeda has a variety of weapons. It can throw asteroids at enemies, send missiles, create a large shockwave and shoot a large green beam. It also has very good armour, as it can only be damaged by break-type chips in the game. Apparently, its anime counterpart is much stronger, as only the Satellite Admins managed to damage it, when they sacrificed themselves.