Hanzou wins with poison and his salamander.... Toads are not good if there is an ocean/sea of salt water..... but idk.
Hanzou will take this he has more battle experience and he defeated the legendary sannin (probably not in prime, yet strong) Also if he fights naruto he will probably know about toad summons and such.
Hanzou will take this, naruto can't cure poison and also every battle he has been in he has been injured somehow, you can't dodge every single attack.
Hanzou wins.