I believe this is the relevant clause:
| i. | East of The Mississippi - any other theme park is limited to using characters not currently being used by MCA at the time such other license is granted. [For purpose of this subsection and subsection iv, a character is “being used by MCA” if (x) it or another character of the same “family” (e.g., any member of THE FANTASTIC FOUR, THE AVENGERS or villains associated with a hero being used) is more than an incidental element of an attraction, is presented as a costumed character, or is more than an incidental element of the theming of a retail store or food facility; and, (y) in addition, if such character or another character from the same “family” is an element in any MCA marketing during the previous year. Any character who is only used as a costume character will not be considered to be “being used by MCA” unless it appears as more than an incidental element in MCA’s marketing.] |
Ant-Man and Black Panther are out - both are core Avengers. I suspect that if Uni wanted to challenge Strange, which they might if Disney pushed beyond pop-up meet-and-greets, they'd have a decent case.