Hardest character to use?

Probably Olimar or Jigglypuff

Bowser or Mr game and watch

I'm going with Pit, he's hard to control sometimes, to be honest.

I find all the heavy characters to be rather difficult to use, with the exception of Donkey Kong, but he doesn't even really play like a heavy.
And of course Snake has to be in this list because his moves break the bounds of traditional SSB play.

quote SPeKTRe

I agree with Avocado. I can't use heavy characters like Ike because they're just so unbelievably slow. People can easily grab you before you do a simple smash attack.

Relying on smashes never works with Ike. He's all about using his aerials, f-tilt, and jabs with good spacing. Those attacks come out pretty fast, have great range, and therefore are hard for your opponent to get past if you space them correctly.

Ike's probably one of the harder characters to use, but to me Snake is really the only one I can never get a grasp on. He's one of the top characters according to most, yet he's probably the character I do worst with haha. He's just too different.

Without a doubt Ness/Lucas ahh

I think ROB is really hard to use. His moves are similar and his Final Smash is kind of boring.
I am also really uncomfortable playing with the Ice Climbers because the
sister/brother always dies before me and I end up weak and jumping off the screen just to respawn my annoying sibling.