If you're going by the manga, Ichigo has control over his demon mask and whips Naruto's ass. Naruto shattered his arm in multiple spots trying to use the ultimate rasengan in the manga, and couldn't even handle multiple uses of it, when confronting one of the akatsuki.
Ichigo has handled the equivilant of that when fighting Byakuya in his Bankai form.
Originally posted by Bol Gath
Naruto while under the influence of the fox is a beast. If he was granted all nine tails or even just 7-8 of them he would destroy Ichigo. You have to understand that the nine tailed fox is one of the most powerful beings in the world, if not the most powerful!
The 9 tailed fox has infinite power, he's stronger by far than the other Jinchuuriki, but he starts doing damage to himself the more energy he channels from the fox. For example in the manga when he fights against Orochi and starts whupping his arse, that was four tails.
Naruto took severe damage from doing that though, and that wasn't even the full 9 tails that would be the full power of the Bijuu.
Originally posted by FortressXRuler
What counts as a win is one of them getting killed. Ichigo has full access to his Bankai and hollow form, Naruto has full access to all of his jutsus and 4-tailed.
Hence Naruto dies. Ichigo has huge area effect attacks he can use if Naruto uses the mass shadow clone technique. Higher end rasengen (ultimate form) is tricky to pull off, hard to hit with, and shattered every bone in his arm in multiple spots. Going 4 tail he loses control and takes damage.
Meanwhile Ichigo with Bankai and Hollow mask is going to be trouncing him. Ichigo is just way to fast in Bankai form for Naruto.
Ichigo seems to operate on a whole different speed level. Most Bleach characters come off as general faster if you ask me. Naruto doesn't have any impressive speed feats either, so Ichigo could easily speedblitz him. Although they might not be AS strong as Naruto's ultimate attacks Ichigo can conjure up some really powerful energy blast.
ichigo wins. but ONLY because he has flash step/speed. ufortunately naruto does not have body flicker technique which would more than counter flash step/bankai.
naruto has far more "power" and destructive potential than ichigo can ever dream. but ichigo's speed will make him victorius as without the kyuubi chakra naruto can not heal from that kind of damage.
Sucks your limiting Naruto to 4 tails, but oh well....
As is said, Ichigo wins due to his speed, however, if he's stupid enough to try and pour his reistu into a single attack head to head with a vicious rasengan, which lets face it, Ichigo might be stupid enough to try... Naruto would warp annihilate him.
That is the only circumstance I can think of where in Naruto wins