Naruto chakra is 5x kakashi so noNaruto needed the Nine-Tails chakra to summon Gamabunta, it wasn't within his chakra level to do it yet. Naruto would need to tap into the Kyuubi's chakra, and one of the main stipulations of my scenario is that Naruto CANNOT use the Kyuubi so this would be impossible.
Even after Jiraiya fixed the seal Naruto was still summoning tadpoles.
It's plausible that there were equal in chakra and that Naruto's Rasengan is just inherently better.Because you said they were equal, I just want to know if you think they was equal in chakra before vote because you know chakra is what make attacks strong and if one is lacking the attack will pale in comparison