Well in reality, Kabuto lost the fight in all aspects. He couldn't beat Tsunade because Naruto interfered, when he thought he killed Naruto, Naruto didn't die. Though Tsunade may have healed him, they also show the seal on his stomach, which implies that Kyuubi had a hand in it. It can be aruged that Kyuubi would've healed naruto on it's own and he would've not died (though he would have at least completely passed out for a while), but since we don't know the extent of the healing abilities (other than he's never been injured for over a day, or something along those lines) I'd rather not make that claim. Also Naruto did knock Kabuto out, and he was probably at least a little humiliated by it (He got all high on the fact that he was against two legendary sannin and it made him think he was on par with them).

Don't take me wrong though, I'm not saying Naruto is stronger. (Though I'm not saying Naruto can't beat Kabuto either, if Naruto got pissed off enough and he was faced with a situation where a loved one was at stake, then he can beat Kabuto)

Don't know if Kabuto could've 'beaten' Tsunade, she didn't even reveal that one technique where she regenerates body cells. She did make a claim that she could never be killed in battle. It's just speculation but if Naruto hadn't interfered, I don't think Tsunade would've died, unless she just didn't want to fight (which is a possibility, because until Kabuto knocked Naruto senseless, she wasn't exactly the most eager fighter on the battlefield) Anyway there's too much speculation that can be taken off of these things. The fact is all the non-sannin were rendered useless by eachother while Tsunade Orochimaru and Jiraiya fought it out afterwards.