Yeah Naruto couldn't Shadow Replicate Gamabunta. At best Gamabunta could maybe Shadow Replicate himself. We already know he can do Henge, and I am sure if an animal could learn Kage Bushin, he could be able to do it. Maybe once Naruto gets a little better, he will be able to Shadow Replicate objects, like Sarutobi-sensei did with the Shurikens, in the fight with Orochimaru..

Also, I don't understand why everyone keeps thinking Shadow Replication makes Naruto stronger. He's just as strong as if there were only one of them. Its not like he is going to beat Kimimaro down now that he has 1000 clones. Each of those clones is 1/1000 of Naruto's power/chakra now, so all what Kimimaro would have to do is use a moderately high offensive ninjutsu that targets a bunch of them and bam their done.

Back to Kiba's fight..I think he and Akamaru will take soldier pills and start going berserk on Sakon. Kiba is no slouch in combat either, he was just unlucky to go up against Naruto during the Chuunin Exam. He isn't a powerhouse by any means, but I think as a Tandem, he and Akamaru are better than Sakon-Akon.