WHO WAS TRAINED UNDER THE BETTER SENSEI'S
NARUTO---Kakashi..Jiriya..Killer-b.
LUFFY---Reighlee..Garp...Jinbe
GON---Wing..Biscuit..Kite
YUSUKE---Genkai..Raizen..
NATSU---Igneel...Gildarts...Makarov
ICHIGO---Urahara...Shinji...Ishhin
Naruto: Kakashi-Jiraiya-Pa toad-Bee-Kurama (taught him the chakra transfer jutsu during fighting in the war). He also self trained
Luffy: When did Jinbe train Luffy? They fought when Luffy was being dumb and when he was going crazy after Ace death. He self trained for the last 6 months after Reighlee left. He also trained himself to master his gum gum powers and improve his physical strength.
Gon: He also trained with Killua family wall guards with Kurapika and Leoron (sp?). Trained himself during the Hunter exam to learn to conceal his presence.
Yusuke: learned how to fight on his own in the beginning. He got trained by his teachers mostly though; you should also add Raizen men trained Yusuke as well.
Natsu: I don't think anyone but Igneel and Natsu himself trained him, he alwaysed tried fighting people like Gildarts, Makarov, Erza, Gray, Laxus, and other guild members but they didn't train him since the fighting was all fun and the strong ones usually 1 hit him.
Ichigo: You for got Rukia training him when he got her powers in the beginning. He taught himself how to fight before getting powers. Yurichi (sp?) trained Ichigo to get his bankai. The Vizards trained Ichigo to use his Hallow mask. The fullbringers trained him to use fullbring.
I added train themselves for those who did because that shows that they had the skills to learn how to fight on their own. I'm automatically taking Ichigo out since Bleach sucks, I mean Ichigo trains but have 1 move which doesn't really have that many variations unlike the Rasengan which have like 20+ different ones and he knows no kidou even though the majority of his masters know them and it never said he was bad at them or anything. They also didn't really teach him much, no new kendo skills/styles except for Urahara.
Luffy learned how to survive in the wild, hand to hand combat, increase his strength, learn and master his gum gum power, learn the basics of Haki.
Gon learn how to access and use the basic of nen, learned his nen type and trained to be that type, learn to use his nen in many different ways which improves his fighting ability, there's more but it's pretty much a ton of different nen training. Wing taught Gon the novice of nen while Biscuit gave him more advance nen training.
Yusuke learn to better use his spirit energy and new moves from his first training with Genkai, improved his strength/speed/ endurance/ stamina/durability/agility/new moves with his second training with Genkai, took her power (spirit orb) in the last training with her. Raizen and his men trained Yusuke in using demon energy and fighting like a demon which increase his overall stat but a lot.
I would say Kenichi's masters from History strongest disciple Kenichi are better because they took a guy with no martial arts training at all (which is stressed a lot since they say it over and over) and made his badas*. He was also a coward for the majority of the manga, he still acts it a bit now still but he's still can beat many people and goes through hell training.
