Last year, Disney announced that X-Men '97, a revival of the popular X-Men animated series, and fans couldn't be more excited. Though the current release is set for 2023, some details have already come out, such as the return of most of the surviving cast.
One thing that the original series was known for was adapting classic X-Men storylines like the Dark Phoenix Saga and Days of Future Past. Should the showrunners for the reboot decide to do the same thing and adapt more storylines from the comics, there are now more than twenty years worth of new comics and material that could be adapted for this series.
Mutant Massacre
An older story that wasn't adapted in the original series, Mutant Massacre features the death of the sewer dwelling Morlocks at the hands of the Marauders, as ordered by the villain Mister Sinister.
The storyline is bleak, dark, and leads to several members of the X-Men getting seriously injured. While an adaption for X-Men '97 wouldn't be as violent as the comic, it would be an interesting experience to the X-Men try - and fail - to save the Morlocks from their fate. Given that Gambit, a member of the X-Men, had a hand in organizing the Marauders in the massacre, it would put him at odds with the rest of the team - particularly Rogue.
House Of M
In House of M, Wanda Maximoff changes reality so that mutants are the dominant species on Earth. After reality is returned to normal, mutants have been reduced to mere hundreds.
As one of the few big comic stories where the X-Men have lost, it would be a little odd to see it take place in the reboot, as the original series rarely showed the team losing any of their main fights. But given the impact this story had on mutants in Marvel comics for years, it could be an interesting experiment to see how well a massive story like this could have. It could even lead into other big events that followed this in the comics, such as Messiah Complex and Second Coming.
The Rise And Fall Of The Shi'ar Empire
Space holds many dangers for the X-Men, even among friends. Such was the case of The Rise And Fall Of the Shi'ar Empire, in which Gabriel Summers, aka Vulcan, overthrows Shi'ar ruler Lilandra and takes control of the empire.
This story could work well to adapt, especially given the ending of the original X-Men animated series, which sees Charles Xavier being taken by Lilandra to heal from his fatal injuries. An appearance by Vulcan where he teams up with Deathbird as he did in the comic and takes over the Shi'ar Empire could lead to another space adventure for the X-Men where they head off into space to save their beloved teacher and stop Cyclops' evil brother.
Curse Of The Mutants
Vampires vs Mutants. That pretty much sums up Curse of the Mutants, where Dracula's son, Xarus, kills his father and united the vampires to attack the X-Men.
One of the fallouts of this event was Jubilee getting turned into a vampire. While vampire Jubilee has been largely unpopular, this plot device could work for X-Men '97. Jubilee was largely a character whose powers weren't as effective as the rest of the X-Men. A vampiric transformation would give her a massive power boost and give her a new story arc as she struggles to contain the monster that she has become.
Inferno
Inferno tells the dark tale of the demons of Limbo invading New York and taking over, causing chaos and mass destruction in the city.
Inferno is another dark story with the X-Men, which the animated series is no stranger to, having adopted Days of Future Past in its original run. While this story might be a little too dark and bloody to be adapted in its entirety, it does give characters like Colossus and Magik a chance to shine - and with both characters appearing previously in the series (albeit in a minor capacity), it does give the showrunners an opportunity to adapt this story.
Schism
The rivalry between Cyclops and Wolverine comes to a head in Schism, where, after dealing with a super Sentinel sent by the new Hellfire Club, the two decide to split, with various X-Men deciding to either stay with Cyclops or leave with Wolverine.
The cause of this split comes from Cyclops wanting to use mutant children like Hope Summers on the frontlines of fights as soldiers, while Wolverine wanting to train the mutant children to use their powers to defend themselves, rather than attack, much like Professor Xavier would've taught them. Most people might have expected their ideals to be reversed - and a twist like that for X-Men '97 would be a nice surprise for the fans.
Age Of X
The Age of X storyline was created by Legion, one of the most powerful X-Men ever, and sees the last of mutant kind holed up in Fortress X, led by Magneto, as humans continue their efforts to slaughter all the mutants on the planet.
Legion hasn't appeared yet in the X-Men animated universe, but with Xavier off world, this would be a good time to introduce him. Given his unstable state, just seeing that Xavier isn't there might be enough for him to snap and warp reality to see his father again. This storyline would also feature Rogue heavily, as she is one of our main focus characters in the comic, as she uses her powers to absorb the memories of the fallen mutants.
X-Cutioner's Song
X-Cutioner's Song featured the X-Men teaming up with X-Factor and X-Force to battle Stryfe, the evil clone of Cable, as well as Mister Sinister.
In the original series, Cable was featured in multiple episodes, as was Mister Sinister, making it more likely that this storyline would be explored. The story also gives way to the revelation that either Cable is really the son of Cyclops and Jean Grey, something that Jean herself may know following the events of "Time Fugitives." This kind of revelation would have Cyclops spinning, and Stryfe being a clone of Cable would make fighting him much harder.
Fall Of The Mutants
Penned by Chris Claremont, one of the best X-Men Writers, Fall of the Mutants sees the X-Men sacrificing themselves to defeat the demon Adversary, only to be resurrected and traveling to Australia under the guise of their deaths.
This comic served as a chance for the X-Men to hide from the world while continuing their mission. How this could work for X-Men '97 would be more or less exactly how the story plays out in the comics. Xavier isn't present, and Magneto isn't working against the X-Men. It would also be the perfect chance for the team to escape from the public spotlight and go underground once more.
Avengers Vs X-Men
One of the more famous X-Men stories to come from Marvel in recent years, Avengers vs X-Men, as the title suggests, pits the X-Men and the Avengers against each other over the fate of the returning Phoenix Force.
While the original story focused on Hope Summers being the host of the Phoenix, Jean Gray becoming the host again is easily adaptable. As for the Avengers, while it's unlikely that the army of superheroes from the comic to show up, a small number of main ones like Captain America and Thor would be enough. Seeing the heroes fight each other instead of villains for a change would be a refreshing and interesting addition to the animated series.