Missing : Mario and Luigi

Well I was sketching in my book and one of the shapes took the form of the Piranha Plant from Super Mario. From there I decided it would be fun to just sketch some more baddies from Nintendo's flagship series. I have to say some of these enemies that Mario (and Luigi - sorta) have to overcome are pretty interesting. Of course over the years there have been TONS of new baddies for this plumbing duo to overcome, but I selected a few that stuck out in my memory.  So who do you think is the biggest threat?

 Piranha Plant: Just got to watch pipes for these guys.

 Bomb-Omb: Child friendly suicide bomber

 Boo-Buddy: Patience is the key, considering you can't hurt them.

 Bullet-Bill: Not sure if he wants to eat Mario or put a hole through him.

 Goomba: Ok I know he can walk, but seriously, how is he dangerous?!

 Koopa-Troopa: General Shock-Troops with a few neat variations.

 Lakitu: Ok this guy was a pain. Even if you managed to miraculously take him out, he reappeared.

 Podoboo: These guys seemed to pop up every time you tried to jump over a pit in one of Bowser's castles.

Shy Guy: I just think these guys are fun looking.