Omnimon confronts Mephistomon (who was formed from Apocalymon's data) in a dark corner of the Digital World over Mephistomon's attempt to destroy both the Digital World and the Real World and incorporate the data in order to become truly invincible.
Digimon: The Movie
Digimon Adventure 02: Revenge of Diaboromon
Digimon Adventure
Digimon Adventure: Our War Game