Shademon is an Unknown Level Digimon that resembles a giant shadow with multiple eyes. He also has an alternate form when it absorbs Nene. It's possible that Shademon also has an alternate form when it's absorbed by DarkKnightmon.
Digimon Xros Wars (Manga)
Shademon is a member of the Twilight Army. It absorbed Nene so it could become more stronger. When this happened, Shademon became a nameless hybird of Digimon and Human, simply known as Nene+Shade. When Shademon became Shademon Darkness Mode, it was presumed that DarkKnightmon Darkness Mode (Duskmon) absorbed it and became, DarkKnightmon Darkness Mode (Shademon). Shademon Darkness Mode eventually digivolved into Moon=Millenniummon.