Vademon is a minion to the Fang Empire. It is shaped like something that came from the far reaches of the cosmos, but it's rumored that it was born from the seed of a plant. It could not be imagined from its enormously developed head and octopus-like lower body, but it carries terrifying offensive power.
When Koushiro "Izzy" Izumi and Tentomon fell into his pocket dimension, Vademon convinced Izzy to give up his curiosity (his heart in the Japanese version) but Pabumon helped Izzy get it back. But at the same time, DemiDevimon wanted Vademon to sell him Izzy's crest. A fight ensued and resulted with Kabuterimon Digivolving to MegaKabuterimon and beating Vademon, collapsing his pocket dimension.
Role in the series
Vadmeon will soon return to battle Spongebob and the Digidestined in a future movisode.