It wourd be cool for Naruto to fight the Rikudo Sage, maybe someone can use Orochimarus reincarnation jutsu.
I"d love to see anyone fight Danzo as long as Danzo dies *grins* Other than that, I'd like to see Gaara/Naruto fight Madara. Or maybe Sasuke fight Madara. Lee vs Neji too maybe.
naruto vs sasuke (all in serious mode).. and i really like if one of them would die from the battle.... :
10-Tailed beast + All of it's many divisions and forms, Naruto and Goku vs Pikachu, Mudkip and Zangief I think the latter would win quite easily.