Before Madara Uchiha came into the decor and screw Shippuden for me , we had the perfect evil . His name was Orochimaru .
And yes , I do not accept that crappy sasuke kill orochimaru ending . I was hoping for a great Naruto vs Orochimaru kinda of battle . Not some episode filled with flash back and one weak orochimaru is defeated by a weakling like Sasuke .
That said , still in the Chunnin Exam Arc , in this episode we see first Naruto fighting something else then a Ninja , and Sasuke fighting something that look like a Ninja but isn’t .
Link to watch : Naruto – episode 29
Naruto's Realm 