I liked it. It was a pretty good topic nonetheless, though perhaps a bit complicated.
So yeah, answer the other one instead.
I would Houndoom. It just looks evil and menacing. Plus alot of it's Dex entries mention that if you're burned by the flames that come out it's mouth, that the pains from the burns never goes away. Forever having burns that will never go away just gives me shudders.
Darkrai is a good second cause it literally lures people to sleep and causes nightmares. Being stuck in a nightmare sounds painful. Plus it has those really long leg that can come out his body. That's pretty creepy if you ask me.