Danny Phantom: The Ultimate Enemy is a video game for the Game Boy Advance console. The game itself is based on an episode of the television series Danny Phantom which is titled "The Ultimate Enemy." The player takes control of Danny Phantom on his adventure to save Amity Park from his greatest enemy, Dan Phantom, who is his alternate future self ten years from the present.
The story opens up ten years in the future in a devastated and destroyed Amity Park. A rogue ghost tears down the city's powerful ghost shield with a mysterious power called the Ghostly Wail. An adult Valerie Gray appears to stop the ghost, and the ghost is revealed to be Dan Phantom, Danny Phantom's evil older self.
Somewhere in the Ghost Zone, two ghosts called the Observants have taken notice of the destruction of Amity Park and comment on how powerful Dark Danny is. A ghost named Clockwork states that "Danny will become a threat to us all." Clockwork then decides that he will make sure that Danny never becomes evil.
Back in present day Casper High, Danny is worrying about the upcoming C.A.T. since he has not had much time to study due to ghost fighting. Sam then appears and tells Danny that ghosts are inside the school. Tucker comments that Danny will grow up to be a ghost hunter and Danny replies that "a ghost hunter isn't a real career path."
After defeating the ghosts in the school, Danny returns home to Fenton Works where Jazz suggests that Danny get to work studying. Danny retorts saying, "You're brilliant and I'm stupid and I'll never be able to get as high a score on my C.A.T. as you did." A ghost suddenly appears behind Danny and Danny yells for Jazz to get out of his room, despite being in the kitchen. Jazz gets the hint and leaves so Danny can fight the ghost.
The ghost then reveals herself to be Box Lunch, the daughter of the Box Ghost and the Lunch Lady Ghost. Danny finds this realization very disturbing ("Eww. That's just gross!") and defeats her but destroys the Nasty Burger in the process by causing the Nasty Sauce to explode. Danny finds a curious medallion Box Lunch left behind when she disappeared. Danny also accidentally phased through Mr. Lancer's briefcase where Lancer was keeping the C.A.T. answer booklet and after finding the booklet stuck to his back, realizes this is the answer to all of his studying problems.
Meanwhile the Observers comment on this development revealing that they planted the test answers for Danny to find. The Observers are convinced Danny will become evil, but Clockwork insists otherwise. The Observers also notice the fact that Danny has discovered Box Lunch's time immunity medallion.
Back in Danny's room, Tucker examines the medallion. Sam decides that the medallion seems futuristic and then asks Danny what he plans to do with the exam answers he found. Before Danny can debate about it, a ghost named Skulktech 9.9 (the future Skulker and Technus combined) appears. Danny then transforms into Danny Phantom and tells Sam and Tucker to find out what they can about the medallion while he goes to fight the ghost.
After SkulkTech 9.9 introduces himself, Tucker comments he can hack into the ghost to stop him. SkulkTech 9.9 leads the battle back to the Nasty Burger and comments that although "The Pummeler" does not work on Danny in the future, it will surely work in the present time. Danny is confused by this but he battles and defeats the ghost.
Using SkulkTech 9.9's time immunity medallion, Danny, Sam, and Tucker arrive in Clockwork's lair where Clockwork reveals himself as the master of time and battles Danny. The trio then determines Danny's turning point was cheating on the C.A.T. Clockwork explains that in the future, Danny has completely lost his humanity. Clockwork states he tried to change Danny's past, but since that did not work out, he'll simply have to kill Danny. Danny, Sam, and Tucker then escape to the future.
The trio are surprised to see Amity Park in a state of ruin and then come across the future Valerie. Not realizing Danny is from the past, Valerie mistakes him for being Dark Danny in disguise and attacks him until Sam and Tucker stop her. Valerie is shocked by seeing them and reveals that in the future they are both dead and claims it was all Danny's fault. The real Dark Danny then appears and claims responsibility for Sam and Tucker's deaths. Valerie tries to stop him but is defeated. Danny tries to save her but is too late. Valerie says that she forgot how cute younger Danny was. And then she passed out. Danny urges Sam and Tucker to take off the time immunity medallions and return to the present before Dark Danny can harm them. Danny is about to do the same when Dark Danny fuses the time immunity medallion inside Danny's body, trapping him in the future. Danny and Dark Danny fight, but Dark Danny then throws Danny into the Ghost Zone in hopes that Danny will never escape.
In the Ghost Zone, Danny realizes his only hope to get back to the present is to find Vlad Masters and pray that he can fix this mess. After finding Vlad's ghost portal however, Danny accidentally stumbles across Walker and his police force and fights them.
Danny finds an older Vlad on the other side of the portal and Vlad explains what happened ten years ago and how Dark Danny was created using the Ghost Gauntlets. Danny then asks for Vlad to use the Ghost Gauntlets to remove the time immunity medallion from his body so he can defeat Dark Danny and set everything right again. Vlad argues that doing such a thing might kill Danny, but Danny comments that he's sure that Vlad can do it.
After his friends and family were killed by his alter ego, he had to live with Vlad. Surprisingly, instead of trying to hurt Danny he sympathized with his pain. After much mental suffering, he wanted the ghost side of him ripped out of his body. It was successfully done, but the ghost was evil and ripped out Vlad's ghost as well. Then the two merged together, and seeing as they didn't need Danny's body anymore, that blew up Vlad's mansion, killing Danny and destroying everything. Dark Danny was born.
After Vlad successfully removes the medallion, Danny returns to the present and rushes to the Nasty Burger to have one final confrontation with his older self. Danny uses the Ghostly Wail, much to Dark Danny's surprise, and traps Dark Danny in the Fenton Thermos. Danny is about to go save his family when he realizes he cannot transform into Danny Phantom. Clockwork appears however and sets everything right again.
At school, Danny turns the C.A.T. answer booklet in to Mr. Lancer and Mr. Lancer decides to allow Danny to take the make-up exam the following week.
- Boxer Ghost
- Looming Ghost
- El Matador
- Bat Ghost
- Devil Ghost
- Dragon Ghost
- Ghouly Ghost
- Splatter Ghost
- Scaredy Ghost
- Ghost Police
- Box Ghost
- Lunch Lady Ghost
- Nicholai Technus
- Dan Phantom
- Skulktech 9.9
- Box Lunch
- Ember McLain
- Vlad Plasmius
- Meat Monster
- Hidden Ghost
- Angry Ghost
- Fright Knight
- Johnny 13
- Observants 1,2
This plot line is not in the show's episode. It also contains more characters from around the TV series, though they never appeared in their original form (not the 10-years-into-the-future form) in the episode of which the game is based.
After completing the main game, if the player selects the file they finished, Clockwork will tell Danny that what he has done still has not changed the future and Danny still becomes Dark Danny. Danny comments, "That's ridiculous. We stopped the explosion!?" Clockwork then tells Danny he must go back to Casper High during the time he fought Box Lunch and figure out why the future is still happening.
Upon completing all missions in mission mode, the source of the problem is revealed to be none other than Vlad Masters; Danny's half-ghost arch-enemy. Vlad explains that Dark Danny came to see him and said "he wanted a little insurance in case the explosion was ever prevented."
After defeating Vlad, Clockwork says that everything will be just fine in the future for Danny now. Clockwork warns Danny though that the smallest thing could start the whole thing over again and Danny realizes it is his own responsibility to make sure this never happens again.
- The game can be finished in a minimum of approximately 2 hours and 30 minutes.