This used to be a long explanation of the multiple combinations of the deck, but with some recent changes a few things have becomes outdated. So, i am going to try rewriting it but also keeping it simpler than the last time.
CORE
Jean Grey: Can't really make a Jean Grey deck without her.
Jeff: He ignores the Jean rule if played first.
Goose: He can force your opponent to play smaller cards if played on Jean.
Havok and Nebula: The meat of the deck, you can certainly replace them for something like Dazzler, Antman and/or Lizard but it won't be the same. (aside from some scenarios)
PACKAGES
Angela, Kitty, Elsa, Hope, Bishop, Silk, Miles, Spiderman: You can mix and match the whole Angela little movers' package, only real key cards is Angela, Kitty and Elsa, so you can find the balance in going more move or more scaling.
Spectrum, Usagent, Man thing, Luke: The ongoing version of the deck is also capable of mix and matching various ongoing cards, core to the plan is usagent and manthing to lower their stats and luke to not lower ours. Havok does clash with spectrum so do keep it in mind if you are playing him turn 4-5 (or you can just kick him for dazzler, antman or lizard as stated above, same for nebula)
Shulk, Sunspot: This one is a bit of a tricky one, but basically you can play havok on turn 4, skip turn 5 and play shulk for 2 energy on turn 6, giving that 4 energy as power to sunspot, is not perfect of course, but is a nice little trick opponent won't see coming.
Cosmo, Armor, Echo: This little shell can be mix and matched with other shells, you basically wanna use two or three of them to create even more hostile lanes for your opponent, which ones you use depends on your taste, but cosmo is usually in all versions if possible.
Debrii, Mysterio, Mockingbird, White Widow, Elektra: Another small package that can cause a lot of damage, you use mysterio and debrii to make your bird free, you also use widow and debrii to clog your opponent and elektra is a nice little surprise for turn 6 to pop one of the rocks and get the -3 power on the widow kiss.
GAMEPLAN
Just as before, the goal of the deck is to create a hostile lane you opponent is forced to play into, which package you decide to use in making the lane hostile is up to you but in current meta (Zemo season) tempo cards with on reveals are fairly common, so the decks shines a little bit more than usual.