Should I just play once on normal, get everything I can, then do it on nightmare on my second playthrought? (will it be easier?) Because so far I'm starting to believe this game is a total piece of crap, damn EA. It is so hard to battle, the dodge is the worst I've seen in video game, it is totaly useless, you dodge an ennemi, and hes like a homing missile, he gets me even if I dodges his damn fork. The last EA game I played was Dante's Inferno, I did it on the hardest difficulty (even if there are no achievement for it -_-) and I was able to do it, even if it is freaking hard. On Alice, I'm stuck on the second level and I can't do it...
Alice has a very forgiving checkpoint system, but some of the encounters are difficult until you have a good feel for the combat system and have all of Alice's weapons (the teapot cannon in particular makes some encounters much easier).
If you're just after the achievement for finishing it on Nightmare, you can always complete the game on Normal, start a new game+ on Nightmare, then use the level select to rapidly skip ahead. --- The man that hath no music in himself, nor is not mov'd with concord of sweet sounds, is fit for treasons, stratagems and spoils. - The Merchant of Venice
One more point - the basic dodge is not a panacea for avoiding enemy attacks. Some attacks track exceptionally well or are downright unavoidable if you don't back away from the enemy or use the appropriate evasion technique. --- The man that hath no music in himself, nor is not mov'd with concord of sweet sounds, is fit for treasons, stratagems and spoils. - The Merchant of Venice