Lol get out man, Sasuke trained like hell with Orochimaru for 3 years, way more than Naruto did. That's how when they met for the first time again, Naruto just got his ass handed over.
How many jutsus did Naruto learn since the series started? 2. Kage bunshin and Rasengan, with a few upgrades. You call that training?
Yeah he got sage mode but so what? He didn't do anything with sage mode, he got his ass handed over to Pain while using sage mode, and after that he never used it again for fighting.
But none of that really matters because Naruto doesn't even use his training or his jutsus to win important battles, he cheats his way through all of them with the Kyuubi's chakra.
Sasuke uses strategies even when using Susanoo so really you can't say he's the one who's lazy.
Let's go through this step by step.
1. When Sasuke met Naruto over the break again, Naruto had just finished fighting Orochimaru and had the 9-tails chakra forcibly sealed back inside of him. On top of that, Naruto was overcome with emotion by seeing his old "friend" again and chose not to fight Sasuke. He never intended to fight Sasuke at all, just try to convince him to return. He also didn't "get his ass handed over" either. Sasuke only had time to stab Yamato before he and Oro teleported away. Naruto and Sasuke never even fought.
2. You claim that Naruto only learned a few rasengan upgrades over the time skip. Quite contrarily, Naruto could effectively go up to 3 tails without losing control. Naruto aged abit and increased his general abilities. The timeskip doesn't seem to have that much effect because everyone else also improved alot. You have to keep in mind though that naruto was on even grounds with S-class ninja like deidara. So it might not have seemed like naruto didn't learn alot because he did not learned any new jutsu, he merely improved his basics which he lacked.
3.He got his ass handed over to Pain using sage mode, you say? I'm not sure which fight you saw, but the one I was watching, Naruto effectively destroyed 5 out of Pain's 6 paths. In fact, Pain was utterly unable to harm Naruto in any way when Naruto was in sage mode, and had to completely wait for sage mode to dispel in order to hurt him. He also used the mode later on when he fought against Kurama, the 3rd Raikage, the 2nd Mizukage, Nagato, Madara, and Tobi's 6 paths.
4. "He just cheats his way through [battles] with the Kyuubi's chakra." If we think back through Shippuden, we will realize that Naruto has not once defeated an enemy relying on only the Kyubbi's chakra. Ever since the time skip, the Kyubbi has only seemed to have gotten in the way, as a reason for Kakashi or Yamato to seal it back within Naruto. He went 4 tails on Oro, but was unable to defeat him then, and if you had read the part of the thread from before, we figure that there is a possibility that Naruto could have defeated Pain a lot more simply had the Kyubbi not been inside him at all.
5. Let's compare a few strategies, shall we?
Naruto vs. Preta, Naraka, and Deva Pain:
Create 2 shadow clones. Place a cloud of smoke. Run towards Preta Pain disguised as Rasenshuriken and have him absorb transformation jutsu. Tackle Preta to ground, making sure to cover eyes, and proceed to crush throat. First clone throws real Rasenshuriken at Deva Pain while the Second clone simultaneously jumps high, out of field of vision, to Destroy Naraka Pain on the way back down with a Rasengan Barrage.
Sasuke vs. Danzo:
Activate Susanoo. Fire Susanoo arrows. Repeat until win.