Just because he didn't kill them doesn't mean he couldn't or in some of these cases didn't defeat them.
Kakashi - Itachi defeated him. (after the sand & sound village attacked the leaf)
Orochimaru - Itachi defeated him. (before Oro left akatsuki) Though it is possible Itachi just cut his arm off and Oro ran.
Sasuke - Itachi let Sasuke win. Itachi was already dieing and he wanted to die at Sasuke's feet, so Sasuke could be the hero that avenged the Uchiha. Anyone that read the manga could tell Itachi let Sasuke win.
Naruto - Itachi & Naruto meet a few times. If Itachi really wanted him, he could of taken him (except when Naruto was with Jiraiya) Itachi was a spy FOR the leaf. He wanted Naruto safe as much as he wanted Sasuke.
As for the others, Itachi didn't fight them at all. 2 of them were already dead.
If you're going to make a serious list, compare the characters to when they could of fought each other. Good Example Itachi vs Jiraiya when they were both alive and right after the sand/sound attack on the leaf. Bad Example would be Itachi vs Sasuke or Naruto, NOW. Itachi is dead and his days of training to get better are over but Sasuke and Naruto are still alive and getting stronger. If you're going to use those kinds of arguments, then why not have Itachi in his prime fight Naruto or Sasuke when they were still children. Yeah, that's pretty "f"ing stupid isn't it.