Ok so return to Beginner City for your Final Challenge. BlackWargreymon stands there and well pretty much has his same story and lines from season 2. Talking about how he's searching for a meaning to his existence and that he's here to end your existence. So he opens a tournament. Breezing through its opponents to reach BlackWargreymon himself. Now BlackWargreymon isn't a pushover. despite lacking the 7s cards he can still put up a fight. Once its over. Watch the not-end credits. Back at Beginner City talking to him again he'll reward you with Veemon's Golden Digi-Egg. (assuming you started with Veemon if not well too bad for you). He respects your power and tells you not to misuse it. Well that's it for this game. Hope you enjoyed.
The only other thing to mention is that Betamon's deck has changed...but he doesn't know how to use it so its not even worth noting him as an opponent.