There are at least two versions of the Disney team up:
One is the Council of Disney Villains led by Maleficent (Hades, Jafar, Ursala, Captain Hook, Oogie Boogie, Pete, Scar, and Hector Barbossa).
Here you and your slave (Kula from Didnapper 2) are errand runners/messengers like Pete, obeying whatever order comes from Maleficent.
The other is the Overtakers led by Hades (Cruella de Vil, Yzma, Jafar, Scar, Ursala, Maleficent, Governor Ratcliffe, Dr. Facilier, and Chernabog.) Here you are a n above average mage and your slave (again, Kula from Didnapper 2 whom you defeated) are intimidated into helping him recover shards of a crystal that could assist him in world domination because... well, he's the Lord of the Underworld.
Fiendish Organization for World Larceny: an interesting twist here is that you, the only human in Duckburg, are a member of F.O.W.L., but as a double agent for S.H.U.S.H. Unfortunately, you've got the eye of Black Heron who is very determined to see you in your underwear.
On the Marvel side:
You are Kang the Conqueror and have just formed Chronopolis into the way it is in Lego Marvel Superheroes 2 (except maybe excluding Knowhere) and have assembled your Masters of Evil: The Presence, Attuma, Shocker, Mysterio, Kraven the Hunter, Doctor Octopus, Green Goblin 2099, Ulysses Klaw, Nathan Garrett, Man Ape, Baron Zemo II, Steel Serpent, the Red King, N'Kantu, M.O.D.O.K, Captain Corbett, and Hammerhead (you smelled Kingpin betraying you a mile away.)
You have 5 choices: