I might be able to do it nowadays, but as a small child, Tekken 1 was a pain in the ass on hard mode. Oh and trying to get Heihachi fair and square is annoying too.

OH and Megaman Zero. I tried and smurfing tried. I had a bitch of a time beating the first boss, the dude with the sword arms or whatever. And then I have to fight the next thing, and I just smurfing gave up. You have these stupid s hitting you down to like 1/4th HP, and right when you walk in on the boss, he spears you in the face and you die. smurf. I almost broke my gameboy over it.

Oh and that one Bomberman Max game for Gameboy, that was annoying at certain times. I did beat it though, and loved it for some reason.