When yiu are naruto if you use harem justu you can easaly kill the first person, you kan also kill kiba and akamaru in 2 hits if you purposly stop the bar in the red and kill him in to hits when kakashi use the summining jutsu on sabusa

If you want to do the Lightning Blade Jutsu first unlock Kakashi and the play story mode as Kakashi.Then work your way to the last stage and you have to fight Zabuza.Now heres what you do you use the Summoning Jutsu and Zabuza will get hurt but he wont stay down so he will attack when the Jutsu is happening.After that the screen will turn white and when it comes back Zabuza will be held by Kakashi's Ninja hound and Kakashi will do the Lightning Blade Jutsu.Try it it works.

To Unlock Kakashi just beat story mode with both Naruto and Sauske and then you will unlock Kakashi in story mode and free mode.