Gambit.

As for the X-Men team, I want it to be the original roster from the comics.

As for a set-up for future movies or shows, just Storm.

If they do introduce Jean and try to do the Dark Phoenix storyline I really hope they do it right this time, I honestly wouldn’t mind a multiple film story like they did for the Infinity Saga where it stretches over 5-10 years and isn’t the main plot of the movies but just in the background eventually building to a massive film like IW and Endgame again.

Jubilee, Kitty Pryde, or Iceman as a ride-along character.

Magneto and Professor X, played by same casts

Def Rogue. Kitty Pryde, Gambit, Beast, Psylocke

Professor X, Magneto, Quicksilver back, Jean Grey, Storm, Mystique, Cyclops, Wolverine, Psylocke, Gambit, Kitty Pride, Angel, Beast, Pyro, Iceman, and Nightcrawler.

Same cast!!! Mcu's not James Bond, no more remake

Professor X, Storm, Cyclops, Jean, Iceman, Shadowcat, Sunfire, Warpath, Beast (Others would join later)