Boogey
In Mission Mode beat Mission 9 in "Tier 4"
Chicken
Beat Story Mode with all characters on any difficulty with 10 hours of gameplay
Clown
Battle 100 times in Versus Mode
Dracula
In Mission Mode beat Mission 5 in "Tier 3"
Eris
Beat "Story Mode" once with either Billy, Mandy, Grim, Or Irwin
Fred Fredburger
Beat "Story Mode" once with either Billy, Mandy, Grim, Or Irwin
General Skarr
In Mission Mode beat Mission 6 in "Tier 4"
Hoss Delgado
Beat Mission 9 in Tier 1 in "Mission Mode"
Jack O'Lantern
In Mission Mode beat Mission 9 in "Tier 2"
Lord Pain
Complete Mission 9 in Tier 5
Mogar
Beat "Story Mode" once with either Billy, Mandy, Grim, Or Irwin
Nergal
Beat "Story Mode" once with either Billy, Mandy, Grim, Or Irwin
Nergal Jr.
In Mission Mode beat Mission 9 in "Tier 3"
Nerglings
Beat Story Mode with all characters on any difficulty
Pumpkin
Get 100,000 damage in Vs. Mode and have all characters complete Story Mode
Vikings
Beat Story Mode with all characters and destroy every letter in the credits sequence