Here are a few criteria’s that make him an awesome villain:
Has a strong connection to hero. We can all agree the hero here is Luigi, and they have been enemy’s when they first met! For 3 whole games King Boos hatred to Luigi has been growing. That’s a connection right?
Has a clear morality. Now if I remember right in Luigis mansion 1. King Boo is after Luigi and Mario because of the countless times they have been hurting his people (The Boos) and his reasons to get back at them are just growing! From sucking up a mansion of ghosts with a cleaning device, to making his whole hotel fall!
A worthy opponent. If we really think about it King Boo is actually pretty darn smart! He lays out his plans carefully start to finish! The only exception is at the end of the 3rd installment. “No more mercy for you, Luigi! No more tricks--no more carefully laid plans! … I'm sick to double death of you! You want to fight me? FINE! Let's go, Luigi! This is the end for you, once and for all!”
They should have a compelling backstory. Now I believe I remember this right but when E.Gadd was younger he caught boolossus, infuriated by this, King Boo raid E.Gaddis lab.
Villians should be fun. King Boo totally has a fun design and is a super cool character. Many of his quotes and reactions are funny to.
So what do you think? For 4 and 5 I kinda got a bit lazy so they aren’t as long, but if King Boo isn’t one of the best villians then I don’t know who is.