What exactly is Sinister's power again?? Doesn't he shoot a beam from the red diamond on his forehead? Dunno how well that'd translate to screen.
Abilities
Superhuman strength and resistance to damage
Shape-shifting
Regenerative healing factor
Telepathy
Telekinesis
Energy projection
Immortality
Scientific genius
Mister Sinister (Nathaniel Essex) is a Marvel Comics supervillain, a foe of the X-Men and related teams. Created by writer Chris Claremont and artist Marc Silvestri, he first appeared in Uncanny X-Men #221 (September 1987).
Sinister is perhaps the greatest geneticist in the Marvel Universe. He is capable of cloning, creating superhuman abilities and enhancing or controlling mutant abilities. His existence is unknown to the general public and he does his research in secret laboratories across the globe. He has employed the henchmen groups the Marauders and Nasty Boys.
Born in 19th century London, Sinister was one of the most brilliant scientists of his day. He entered a pact with the centuries-old mutant Apocalypse, who granted him immortality, among other powers.
However, Sinister has no allegiance to Apocalypse and, studying the bloodlines of the X-Men Scott Summers and Jean Grey, determined that their child would be a mutant powerful enough to destroy Apocalypse. When Grey was thought dead, Sinister created the clone Madelyne Pryor to bear the child who would become Cable. Sinister also has a connection to the X-Man Gambit.
Sinister was a frequent villain in the 1990s-era X-Men animated series.
You can't have Mr. Sinister without Apocalypse. Which is why I think it'd be best to include both of them in a future sequel or a restart.