A lot of the same strategies apply when fighting in normal or difficult mode. I just got through difficult mode tonight with two other teammates (I'm LV67 Wind, my teammates were LV69 Fire and LV66 Water), and the only differences across modes is the addition of more rounds to fight. We ran with clone spammers to serve as extra hits and as hit absorbers for Giants/Jiraiya/Hanzo, and it worked out well because we got better combos.
Round one is the Giants, and round two is Shizune with ~56hp. Round three is Karin, with 56 hp as well, and you approach her the same way you'd approach Shizune. If you're in difficult mode you have to fight Sage Jiraiya (who puts the Ignite debuff on all ninja who attack him) and this is where most people fall because they don't have a decent healer who can negate debuffs or heal the poison + ignition stack damage. If you have Sakura, Tsunade, Kabuto, Water Main, etc. this can be avoided easy, as his hp is scaled like normal battles. And Hanzo is the last round, by his lonesome and also with normal hp.
Normal and difficult mode is all about combos and timing, same as easy mode, but you have to be precise about everything otherwise it won't work.