Yeah, school me. Give it a try!
The entirety of Naruto's skill set and tactics all fall in the line of hard core and intense training, aside from the powerup given by Hagoromo and Bijuu Mode.
Before I even make a deep analysis, Naruto would never have had the stamina/chakra to pull most of these techniques off by himself. His own chakra was mixed in with Kurama's, so at an early stage he was already being pumped by the Kyuubi thanks the 4th. Naruto was never really born a genius, he was just born lucky in a sense. Always given the right pieces in play.
Shadow clones > Naruto had to train for hours (or was it all day and night?) just to master the technique.
Rasengan > Do I have to explain why this technique took such an ample amount of time? It lasted the entire Hokage retreival mission arc just for him to learn it, and mind you he only peformed it once at the last minute before the arc itself ended.
Summoning Jutsu > His first try he summoned a tadpole, and it took quite a while for him to master the technique, and even that he could not do without Kurama's chakra.
Rasenshuriken > Same with the Rasengan except watered down due to the shadow clone method, he still had to train incredibly
Time skip > Mastering his already known skills to a new level.
Rasenshuriken > Self explantory
Sage Mode > Self Explantory
KCM > Could not do without the help of his mother, and Killer Bee.
Shushin (KCM) > Had to get used to moving at incredible high speeds
Bijuu Mode + Sage Mode > Did not come "naturally" --It wasn't hard to begin with, Kurama noted that it did not work earlier because Kurama would not synch his body with Ma and Pa. Though now that Kurama trusted him, you can understand the rest.
BIjuudama > He trained throughout the War Arc, and that mastery applies when he learned BM. It wasn't instantly granted, Naruto had to master the chakra ratios.
Most of Sasuke's training in Part 2 came from MS/EMS - Mind you, that was not really training at all.
1. Ashura was never a genius, so simply being a transmigrant wouldn't guarantee this trait.
2. Naruto worked 1000x harder than Sasuke because he's not a genius, while Sasuke was.
Exactly Lol
Ashura was a failure, he needed the help of cooperation to even match his brother.