Sweet Mother of Mercy!
Like that dude couldn’t be even more terrifying. Ghetsis is my favorite (and probably most vile) of all villains from Pokémon mainstream games. :3
The you drew him is a perfect reflection of this guy soul. If whatever has inside could be considered a soul. XP

Good to see that I'm not the only one who has Ghetsis as my most favorite villain in the core series (my runner ups are Piers and Archie) despite how toxic he is.

Well he undisputedly the most sinister of them all. The other leaders, seem to have more a sense of honor when it comes to Pokémon Battles. Like a duel between respected opponents they acknowledge your skill and accept defeat and it's terms. Each seem amused by battling such a young trainer being so strong.
Ghestis however, is not. His main goal is to get more and MORE power over Unova. He cares not about honoring any terms of defeat nor is amused by battling such a strong opponent. You are just another obstacle to removed. Everything is just a means to an end, or a pawn to be used. Where the other leaders appear to have some sense of honor or standards Ghestis doesn't care. He only wants absolute power and will do anything to get it.
Abusing and manipulating a child to become a 'King' through which you hold all the strings? Done.
Freezing the entire city and its inhabitants just to get a gene splicer? Done.
Trying to freeze (impale) a child to secure his goals? Done.
While there's no doubt the other team leaders are evil/misguided or crazy to some degree I think Ghestis is just straight up insane. To me that makes him the most terrifying to deal with so far.