Sorry to spoil the magic, but it appears that Constantine was the only actual Disney
villain roaming the park. Constantine' s right had man Matt Vogel was there so the amphibious fiend was able to talk directly to fans and take pictures. All the other Villains "in attendance" were the standard Disney walk around costumed characters. Definitely a win for Muppet fans.
Attractions Magazine got a great video of their encounter with the world's #1 criminal.
Inside The Magic also has clips of all of the villains in attendance with a short bit of Constantine at the beginning.