Pokemon? The one where the main character doesn't age? Where after every region his favourite pokemon gets reset to Lvl 15?
Yeah Edo Kages were simply too powerful to be defeated so easily.
Even if you are talking about the anime, in order to achieve legendary status you need to be very popular and no matter how you look at the anime, a lot more people will recognise Pikachu then Naruto. The quality doesn't really matter, as long as the fanbase is big. IMO Dragon Ball = Pokémon when you look bluntly at the storyline, they both suck. You are tellling me that the main character doesn't age is a valid point against the anime. Well Goku vs Frieza took 19 episodes before they finished their fight: 19x20= 380 minutes=6 hours and 20 mintes. You can't tell me that that Goku talked/fought non stop for 6 hours and 20 minutes against Frieza. Both time lines are screwed up.
Death Note = legendary? Show a random person both pictures of Pikachu and Ryuk, lets see who gets recognised most often. And Naruto's anime is more sh*tty then that of Pokémon. Every epic scene was screwed up by the anime studio. Or are you going to tell me that Edo Madara's emergence and Tendo Path vs 6 tail cloak Naruto were good?
Last but no least: pokémon manga > anime and when you talk about legendary in temrs of storyline then, Naruto would be considered completely sh*t since lots of mangas will crush Naruto with their plot.
Edit: if you are talking about legendary in terms of popularity then you should really think twice before saying Naruto>Pokémon.