Role in the Games
Alphamon acts as the main antagonist of Digimon World DS, where he goes by Unknown-D. He disapproves of humans taking care of Digimon as Tamers because he believes humans make Digimon weak. To carry out his plans he seeks the legendary Digimon, Chronomon but it turns out to be a force that he cannot control.
Alphamon appears as a boss alongside Omnimon and Gallantmon in Digimon Story: Cyber Sleuth, and can be unlocked by digivolving from DoruGreymon. A female Alphamon is one of the main protagonist of digimon story cyber sleuth.
Role in the Anime
In Digimon Adventure Tri's first movie, "Reunion", Alphamon's silhouette is shown defeating Davis, Ken, Yolei and Cody, seemingly destroying their D3s in the process.
Alphamon's hand is later seen at the end of the Kuwagamon battle, where he crushes the final Kuwagamon from within the Digital World.
Alphamon finally makes a full appearance in the real world at the end of the movie, attempting to hunt down Meicoomon and prompting Tai and the other Digidestined to come to its rescue. Eventually, WarGreymon and MetalGarurumon DNA-Digivolve into Omnimon, who, after a brief clash, makes Alphamon retreat back to the Digital World.