For the attraction, it's easy to see how it'll be a "best of" experience with different scenes tied to each villain. Maybe Maleficent has sent out a recruiting call to gather up all the Villains to take over the realm of fantasyland... only to then battle each other for labeling themselves as the "top" villain?
The land should be more akin to the "traditional" mashed up styles of Fantasyland and Adventureland. I think Adventureland is a perfect model of smaller "sub lands" within a general theme (Colonial, Polynesian, Arabian, Spanish, etc.). Avoids the SWGE problem entirely.
The coaster could be an abandoned transport vehicle that has been turned into a tour of the caverns/hidden pathways the villains use to train/hide.