Do you think he can form rasengan with no bunshin now? Why you might say yes: In his fight with Itachi, Naruto lunges at him with a Rasengan already formed in hand. No bunshins in sight. Why you might say no: In his fight with Deidara, Naruto lunges at him with a bunshin. My thoughts are, Naruto can perform rasengan with just one hand. He did train for 2.5 years and his chakra control would have improved. If Naruto uses a kage bunshin to do a rasengan, it would logically be faster and easier to do (instead of control your chakra to randomly spiral, you use a bunshin to randomize the spiral). Besides, a kage bunshin would helpful during the attack.