Introduce Morph the way Jubilee was introduced in the 90s toon. Stryker steals Sentinel tech and reactivates the program. He tries to kidnap Morph, but Jubilee intervenes. She and Beast put up a fight to save Morph, but Jubilee gets captured.
Meanwhile, the other X-Men try to save Mystique and Magneto, who have been captured by Mister Sinister and Sauron after being ambushed while fending off Omega Red. Beast and Morph get (an obviously recast) Rogue and Wolverine (also recast) to help them save Jubilee, and Styker's carelessness leads to the plots converging in the Savage Land.
Boom! Instant 90s X-Men nostalgia glory in a 2018 live action film!
Get a different director too. And let Mystique wear clothes for once! Gambit appearance optional.
For the follow-up movie in 2020, have D'Ken Neramani as the villain, and adapt a proper Phoenix Saga. As for the Dark Phoenix? Adapt "One Man's Worth" first, then adapt the Dark Phoenix. And get it as close as possible to the toon, because nobody wants a repeat of "The Last Stand."
Who's with me on this? Fox, you have the source material. You even had a whole programming block in the 90s featuring this material. Use it already! (90s suits optional. I know it won't be easy to get away from Singer's black leather fetish.)
Also, get a new director. Singer is stale and predictable now:
Prof and Magneto play chess, the plot gets convoluted, the characters get a get-out-of-jail-free card by Wolvie and/or Mystique getting naked and kicking everyone's ass, a plane will crash somewhere, Angel has no shirt on, Colossus is half-naked half the time, Beast hates his own fur, Cerebro gets hijacked by the bad guy, blah blah blah ad nauseum!
- Jubilee actually does something!
- Mr. Sinister
- a new director
- Other (explain)