The stupid thing about this question is that while an enemy, let's say Bombs, might be hard in one game, in another they're not.
For example, my whole FFIV game is essentially hard, I'll have to say, so Bombs are relatively harder there than, let's say, FFVIII, where I basically anihilate them in a few hits. Why is this? Because of the different mechanic of the games.
You can just reduce an enemy to the type of enemy. What is hard, or annoying, in one game won't be in another.
Also, reducing the giant array of dragon-like enemies to a single class like that sounds really bad. Just saying.