well....there's already been a long discussion about how naruto most likely used kyubi to summon gamabunta.....but the reason for him being able to call upon so many clones and from a jounin level jutsu no less is because having the kyubi in his body since birth allowed his body to adjust to the large amounts of chakra and give him an overall larger chakra stamina....if he never had the kyubi inside him, then he not only wouldnt have the red chakra, but he'd have less blue chakra too