Moon=Millenniummon

Moon=Millenniummon is an Evil God Digimon whose name and design are derived from "Moon-Millenniummon". It is a soul Digimon that exists within Millenniummon's inner world. As a result of Millenniummon's dark spirit becoming a Digimon, it does not possess a fixed form, and although it often takes the shape of a crystal, it seems that the hatred and anger it feels against those who oppose it cause it to change shape. As it is a soul and does not have substance, it is immune to physical attacks. Even though its physical form, Millenniummon, must have been defeated first, there probably aren't any Digimon that could defeat Moon=Millenniummon; even if Millenniummon is somehow defeated, it is said that Moon=Millenniummon will separate from its now-dead physical form and be revived throughout time and space.

Digimon Adventure 02: Tag Tamers
Moon=Millenniummon digivolves from MetalGreymon in line 37.

Digimon Adventure 02: D-1 Tamers
Moon=Millenniummon is the final boss of Digimon Adventure 02: D-1 Tamers, as well as a playable Digimon.

Digimon World Data Squad
Moon=Millenniummon apears as a boss in the Dark Area, after its defeat, you will obtain the Blue Jewel.

Digimon World Dawn/Dusk
Moon=Millenniummon digivolves from Kimeramon. Kimeramon must be in level 66 or higher, spirit must be 380 or higher and you must have or had a Millenniummon. Moon=Millenniummon is one of 3 opponents in the Silver Rank battle.

Attacks
 * Death Crystal: An incorporeal attack that is said to cleave apart the opposing Digimon's spirit.
 * Dimension Destroyer