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.