Universal doesn't have all Marvel,
It's closer to "just" the comic book Avengers at the time of the agreement...or something like that.
In terms of movies, here is a good graphic:
In terms of Parks, it's a bit more.... complicated.
http://www.sec.gov/Archives/edgar/data/1262449/000119312510008732/dex1057.htm
The short answer: In Japan and the United States east of the Mississippi: Universal has the rights. Elsewhere in the world: Disney.
The long answer however is that Universal has to upkeep and maintain certain levels to retain those rights or they revert to Disney. As long as Universal maintains it's part of the bargain, there is strict language against Disney (or Marvel) opening any rides, simulators or other attractions within a certain radius of any Universal park.
There is some language that gives some outs:
Each THE MARVEL UNIVERSE shall be operated and maintained in a first class manner consistent with the highest standards of the theme park industry and shall be deemed “open” only when operated in such manner (subject to temporary closures for force majeure events as described in the prior paragraph).
At such time as any THE MARVEL UNIVERSE is no longer open at a particular Universal Theme Park, all exclusivity and marketing rights acquired by MCA as a result of the opening of such THE MARVEL UNIVERSE at such Universal Theme Park, as set forth in Section IV below, shall terminate and this Agreement shall thereafter be construed as if the notice of intent to open THE MARVEL UNIVERSE had not been given by MCA.
In other words, If Disney can prove that Universal has let the quality slip below "first class", they can deem the ride as not "open" and can terminate the agreement.
Regarding what characters they have, that's where it gets interesting:
Universal Theme Park (Orlando) and an exclusive world-wide option to utilize the Marvel characters in additional THE MARVEL UNIVERSES in any other Universal Theme Parks, which initial option must be exercised during the two year period beginning on the date of the opening of THE MARVEL UNIVERSE in the Universal Theme Park (Orlando). The present inventory of the Marvel characters is set forth in the schedule to be attached or provided by Marvel promptly after execution hereof, plus any characters developed or acquired or licensed in the future by Marvel which (x) are marketed under the Marvel “Banner” or (y) were previously marketed under the Marvel “Banner” during the term hereof and are subsequently marketed under the “Banner” of a Marvel Related Company (defined below). Any characters which are licensed to Marvel by third parties subject to terms which require Marvel to pay a license fee based on revenues or which do not permit sublicensing may be excluded, at Marvel’s option, in the foregoing grant.
After such 2 year period, MCA’s exclusive rights will be subject to “shrinkage” or “expansion” as follows:
1. If no action is taken by MCA, such exclusivity shall be limited as follows:
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.]
So any character or character family that was not represented at Universal is open to Disney east of the Mississippi (i.E. Guardians). Any new characters acquired or created are open to Disney. Any character that was only represented as a costume is open.
It goes into more detail, but you get the gist of it.