It was foreshadowed since part 1 that naruto will gain the control of kyuubi chakra one day.naruto learnt sm by training and it took him a decent amount of time.just like that ass pull 4th hokage chakra mode or sage mode?
What are you even talking bout?
Sasuke received all bijuus chakra from nowhere.that was the biggest asspull even blind madara's susanoo pale in comparison to it.