Unlock Darth Vader & Princess Leia
To get Darth Vader you must complete the game 100%, to get Princess Leia you need to complete all of the Mystery missions in the game (not just in one park, ALL of the parks...same with Darth Vader)
Unlock Zombie (Avatar Costume)
To unlock The Zombie you must complete all of the
missions on Thrillville Chills.
Unlock Sinsister Tim
To unlock Sinister Tim you must complete all the Park Management Missions on Thrillville Villainy.