While there was just three well-known mutants highlighted in Deadpool, it looks like FOX upped the anty with ore mutants. Not only X-Men this time but what looks like X-Force. Deadpool is determined to save a boy Russell from time-traveling Cable gets in the way. Everyone already knows Cable, son of Scott Summers from the comics so here are some more...
Domino (Zazie Beetz) has the power to change probability. It seems like a strange power at first but it's proven useful to Domino in combat, giving her unparalleled marksman abilities (She never misses) and helps her get out of most situations unharmed. In the comics, Domino is the result of a government breeding program like several others in the X-Men universe. After escaping the program, Domino became a mercenary, working with a group called Six Pack, until she eventually joins the X-Force. Deadpool 2 has changed her ethnicity, hence changing her well known eye makeup.
Bedlam (Terry Crews--Brooklyn Nine-Nine) has bioelectric abilities that allow him to disrupt and affect electrical systems. He's also trained in hand-to-hand combat. Jesse Bedlam is one half of the X-Men comic's Bedlam brothers. After being orphaned, Jesse is separated from his brother Christopher, placed in a psychiatric hospital, and tortured. He is eventually rescued by Professor X and placed on a mutant task force called M.U.S.E. Later, Bedlam teams up with Domino to track down his brother, then joins Christopher's mutant team New Hellions, and finally switches to join the X-Force to stop Christopher from reviving Armageddon Man.
Negasonic Teenage Warhead and Yoiki/Surge (?)
The Negasonic Teenage Warhead (Brianna Hildebrand) we see in the first Deadpool movie is different than the one seen in the comics. In the movie, Negasonic works with Colossus, using her explosive powers to help Deadpool rescue Vanessa. In the comic books, Negasonic Teenage Warhead has telepathic powers and dies a lot. Negasonic can bee seen wearing X-Men gear in the trailer for the sequel. She is also seen accompanied by a pink hair mutant by the name of Yoiki (Shioli Kutsuna). It is said she is her girlfriend. She electrifies her metal chain in the trailer. Some sources say she is based on Surge, an obscure Japanese X-Men who manifests electricity-based powers.
Shatterstar (Lewis Tan) has superhuman strength, speed, agility, durability, healing, and more. He can also generate bioelectric shocks, which channels into objects, most often a sword he carries. This ability makes Shatterstar an especially powerful fighter. Shatterstar is a mutant created by bio-engineering in another dimension called Mojoworld, where he is an enslaved fighter. After escaping, Shatterstar tasks himself with defeating Mojo V, the ruler of Mojoworld. In his quest, he meets Cable and joins the X-Force after he is assured that the team will help him defeat Mojo.
Zeitgeist (Bill Skarsgard--Pennywise from It and brother of Alexander Skarsgard) has the power to spit acidic vomit from his mouth, which can burn through any substance in the world. In the comics, Zeitgeist is a leader in the X-Force team. After becoming dissatisfied with the team, he plans a mission that will kill most of the members of the X-Force but it goes awry and Zeitgeist is eventually killed himself.
Footage showed that Russell (Julian Dennison) has pyrokinetic abilities, meaning he can control and create fire out of his hands. Some fans believe this kid could be Russell “Rusty” Collins, the mutant also known as Firefist. Other mutants were guessed to be but ultimately Firefist seems to be the closet character.