I believe Fox, not Disney, owns Deadpool along with all the rest of the X-Men movie universe. (Which is why Scarlet Witch of the Avengers is not considered a mutant in the Disney movies.) Even though Marvel developed these superheroes — Avengers, X-Men, Spider-Man, they only own the Avengers movie rights which Disney was able to obtain when they bought Marvel.
Sony even owns Spider-Man. Disney owned Marvel and Sony have worked out an agreement for Spider-Man to appear in the Avenger movies. They are supposedly trying to work out something with Fox concerning the X-men.
Very interesting. Didn’t know all that. So who owns Iron Man, Thor, Ant Man, and Guardians?