DPR is structured around three 20-episode seasons (with the idea that each episode fills a 30 minute time block). This of course can be shortened or lengthened.
S1E1: Auto-Pilot: A Fenton-Tech, Ghost-Hunting AI overtakes Skulker's mechanized suit and starts hunting Danny. Danny is in denial about being a ghost, and believes they're everything awful his parents have told him. Skulker and Danny have to work together to defeat the AI. Danny discovers a blocked off room underneath Casper High that becomes the trio's main base of operations in the future.
S1E2: Immolation Technology: Every time a ghost attacks, Jack and Tucker feel upstaged by Maddie and Sam on the field. Computer-based Technus escapes from the Ghost Zone and traps Danny, Maddie, and Sam within a cybernetic prison; safely out of the way while he takes over the town. Jack and Tucker realize their strengths lie in tech, not physicality, and save the day.
S1E3: Uprooted: Maximillian Baxter and his son, "Junior," have just moved to Amity Park. Dash becomes the ruthless new bully-king of Casper High. Sam decides Max has gone too far when he unveils his plan to build a Gold-N-Diamonds on top of Amity Swamp; she equips a powerful ghost artifact once belonging to Undergrowth to scare him off. Sam gets enveloped in her rage and plant-based abilities, leaving Danny Phantom, Tucker, and regrettably Dash to break her out before the entire town succumbs to nature.
S1E4: Dogfight: Danny encounters the Red Huntress for the first time since he's been superheroing. When Dolly Day and her pet Wulf threaten to riddle Amity Park with portals to the Ghost Zone, Danny and Valerie have to work together.
S1E5: Sharing is Scaring: After seeing Danny struggle with superheroing and schoolwork, Sam and Tucker go hunting for a wish-granting ghost named Desiree, and ask for powers similar to Danny's. At first, all goes well-- but without any humans to throw off ghost scanners or fill in for Danny's attendance, everything starts falling apart. Worse yet, Desiree only grants wishes to humans, and has followed Sam and Tucker out of the Ghost Zone. The trio has to trick Desiree into undoing the wish before she becomes unstoppable.
S1E6: Polterguidance: School counselor Penelope Spectra infects Danny with a disease that leaves him bed-ridden. While his family frets over his health, Danny discovers two new powers- he can walk outside of his body, and he can possess other peoples' bodies. Suspicious of Spectra, he discovers she is a ghost feeding on the lifeforce of Casper High. Danny resorts to possessing various students at Casper High, using their bodies to battle against Spectra and ultimately send her back to the Ghost Zone.
S1E7: Band Freaks: Casper High's annual Battle of the Bands has been infiltrated by Ember McLain. When she hypnotizes the school at her debut concert, the only students missing are Tucker (perfecting his video game technique) and Dash (who spent that night, in secret, listening to the new album of his favorite boyband). Tucker and Dash work together to broadcast a spunky boyband pop song over the ecto-infected PA system, giving Danny enough time to snap out of it and defeat Ember.
S1E8: Femme Fatal: Sam's hatred of all things girly is cranked to 11 when Tucker and Danny aren't there for her to complain with. Luckily, she meets Sidney Poindexter, the ghost of a nerd who haunts Casper High, and they work together to make queen bee Paulina's life a living hell. When Sam and Paulina are forced to serve weekend detention, however, the school is way less friendly. Sam realizes that Sidney in life wasn't snubbed for being a nerd at all-- he just had a superiority complex over every "popular kid" around him. Sam and Paulina overcome their differences to defeat Sidney and escape the haunted school.
S1E9: Academy Award: Jazz goes out of town for the academathlete finals, and Danny, afraid of Wulf attacking her, goes with. Danny does a horrible job of hiding his secret identity, but Jazz rationalizes all the ghostly shenanigans away, until Wulf attacks their hotel room and she sees Danny transform. Danny's initial panic over his secret being revealed is cut short by Jazz giving him a hug, saying she'll always accept him.
S1E10: Birth of a Phantom: Danny's 15th birthday. Flashback to this time last year, when he followed Plasmius into a strange room and first gained his ghost powers.
S1E11: The Tragic School Bus: A field trip to the museum goes awry when the entire class is pulled into the Ghost Zone. Marcel Walker, "warden of the ghost zone," is fed up with Danny Phantom invading the human realm and seeks his capture. Unable to reveal his secret identity, Danny, his classmates, and Lancer all work together to escape the Ghost Zone.
S1E18: Aesop's Fables: A series of shorts centered around Lancer, showing how Casper High exists and works outside of Danny's friend group.
S1E19, S1E20: The End of Amity: A two-parter. Walker pursues Danny out of the Ghost Zone and into the human world. Casper High is destroyed in a fight. Danny cannot rely on his powers; he has to work with his parents as Fentons to finally defeat Walker. The town can no longer pretend ghosts don't exist.
S2E1: Ghost Town: Valerie is researching ghost-hunting and finds a collection of letters from the 1800s. A flashback episode about Walker when he was alive, his battle with the Fright Knight that turned him into a ghost, and how he founded the White Walker organization. Valerie ends the episode joining the WW.
S2E?: Fright Knight: Jack and Maddie have Danny wear ghost-hunting gear for the annual Fenton Family Halloween Ghost Hunt. When the ghost Fright Knight attacks, everyone in town begins literally turning into their costume. Danny has to rely on Dash, the one person who dressed up as Danny Phantom, to save the day, before Danny himself becomes so Fenton-like he starts hunting him down. Dash realizes Danny's secret identity.
S2E10: Year One: A flashback episode. Vlad's college experience, gaining his ghost powers, and being betrayed by Jack and Maddie.