I found the elevator fight and the final fight to be the hardest (since). In the Ivy fight, her vines come out centered around wherever you're standing. I'd fight all the way in the left or right, then roll to center when the first vines came up, then again to the opposite side when the second vines came up.Joker wouldn't turn around unless at least one of his thugs was still fighting you, and if one of his thugs was still fighting you, you couldn't pull him down
One trick in Arkham Asylum, if it's not too late, is to hold off on upgrading armor as long as possible and save an upgrade point for a boss battle. Upgrading your armor increases your maximum health and heals you to full, so, you know, maybe now's a time to use it? Ivy at least heals you to full halfway through the fight.
Oh god I had completely forgotten about the elevator fight, so much RAAAGGGEEEE
I already finished the game, but thanks for the advice. Guess that will also work in Arkham City?