Naruto Uzumaki: Would put his years of practice as a prankster to work, using misdirection and Shadow Clones to lay clever traps that he thinks up on the fly as circumstances change (to contrast him with Shikamaru, who plans everything out far in advance). More than one or two of his wins would come from using comical or basic techniques in unexpected ways (in canon he did stuff like using Thousand Years of Death to stick an exploding tag on Gaara and distracting Kagura with Reverse Harem no Jutsu. So like that, but more than once a story arc). Also, someone teach this kid a justu that isn't Shadow Clone or Rasengan! And no, summoning, kyuubi chakra and derivatives of the above don't count. And if he's going to use a weapon, my preference is for a Chakra Knife like Asuma had: he's already got the wind nature to use it, the chakra to abuse it, and it suits him much more than Zabuza's big honking Buster Sword, which bad fanfics seem to revel in giving him. As a fighter, Naruto should always be moving, always be agile, and when he's on the offense he should be in really close hand to hand. If he's inherited the Uzumaki knack for seals, he should add that to his repertoire and use that to support his other skills (like finding a way to seal natural energy so he's always got reserves of Sage Chakra to whip out, or to lay much better and more powerful traps).
Sasuke Uchiha: Honestly not that many improvements to make, though that's largely because Kishimoto wanked him so hard I'm surprised his dick didn't fall off. Aside from making more use of genjutsu (but he would have a thing about ever using Tsukuyomi on someone) and maybe using a sword more often and from an earlier point (it really suits him, and goes well with his Lightning nature), he's pretty much set.
Sakura Haruno: Supposedly she's got a lot of talent with ninja arts that require precise control like genjutsu. By the Sage, use it girl! Sakura should basically fight like Shikamaru, but much more hands-on. She's got a lot of potential (taijutsu, medical ninjutsu, genjutsu, strategy/tactics) that she never fully utilized. So where Shikamaru wrings every bit of us out of his rather limited (but endlessly versatile) bag of clan-art tricks in canon, Sakura would be a jack of all trades (though she'd still specialize as a medic) who may not have a jutsu that's exactly the right thing for the situation, but always has something that will work, given a little bit of thought. She'd be in-between Naruto and Shikamaru in terms of tactics: she always has a plan going in, but improvises as the circumstances change. By the end she'll have really surpassed Tsunade, becoming not just the best medic-nin, but would also be somewhere in the Top 3 or 5 at everything else.
Hinata Hyuuga: That technique she created for Juuken was pretty cool; more of that, to make her an absolute demon in close-quarters while still keeping her distinct from Neji (probably have her concentrate on overwhelming defense to wear them down and then capitalize on an opportunity, where Neji is all about using pinpoint precision to break through their guard like it isn't there) Those all-seeing eyes of her would make her a fantastic ranged combatant (she'd be an absolute beast of an archer, especially if it was some kind of special bow that made arrows out of chakra so she didn't need to reload). Combine that with learning genjutsu (come on girl, Kurenai's your sensei and you're her favorite student, don't let her down!) and she'd be set for most of the series. I suppose if you really wanted to buff her up into a powerhouse you could change the Tenseigan so that it's more like the Mangekyo and have her unlock that when she stands up against Pain or Obito, but I'm ambivalent about it.
Kiba Inuzuka: Like I said, he needs to stop broadcasting all his attacks by making loud full-frontal assaults and fight like a real predator. He and Akamaru should fight like a wolf pack: surround the enemy (well, not surround in this case, but force him to split his attention between two targets), strike when he turns his back, wear him down until you can go for the kill. He also needs to use hit and run and ambush tactics: strike when they don't expect it, disappear, then do it again when they're not looking in the right direction, again with Akamaru further splitting their attention. He could also stand to learn some extra ninjutsu, maybe fire nature, to give his attacks more oomph (Fiery Fang Over Fang!). In the endgame he could also build enough chakra to use more than a single shadow clone (speaking of those, BTW: cleanly dividing your chakra evenly between them is bullsh*t and so is you getting all their memories. Seriously, f*ck both of those, they're retarded considering the number of them Naruto and other ninja pump out and they make Naruto a complete and utter retard for needing to be told to use them to train, plus the latter makes Naruto utterly, absurdly broken unless you make him a complete and utter retard).
Shino Aburame: Pretty much the only one I think doesn't have much of a pressing need to change, though some diversification would do him all kinds of favors. His best bet would be to add some genjutsu to his repertoire to camouflage his bugs and the like, and maybe some earth nature ninjutsu to make him less squishy and give him some offensive options if he ends up getting hit or can't use his bugs in time. Hell, imagine if his bugs could burrow. They'd burrow under the ground and then come spraying out in a wave at you, or sneak up your feet to inject crap into you.
Shikamaru Nara: Give him a lot more team battles to actually make use of the vaunted Ino-Shika-Cho teamwork, and his vaunted potential as a commander. He doesn't have to master it, but he should definitely pick up some genjutsu to round out his clan art-heavy loadout and give him more options to outwit and mess with opponents. It's especially fitting since Shikamaru's ideal fight isn't just one he's won before it starts, but one that he doesn't have to move around much to actually win. Most of his genjutsu would just be ways of misdirecting and maneuvering opponents so that he can more easily grab their shadows. Like, say, make them think a light source that doesn't exist is there, or make them not see one that is there, and also change the shadows so they don't notice until he's got them. Towards the endgame he'll take the support role, almost exclusively using his abilities and brain to set other people up for the finishing blow.
Ino Yamanaka: As with Shikamaru, she'd fight in far more team battles to make better use of her support-type skills. Make her the information expert: she's got the brains, the social skills and the jutsu to be an absolutely terrifying intelligence agent. If all goes well, she should never fight alone, and if she does she'll prefer to get away or fend them off until help arrives. Not that she'll be helpless in a brawl: making her Tsunade/Sakura-lite with medical ninjutsu and taijutsu like in canon is a good way to up her effectiveness. Even better is for her to also use a lot of genjutsu, which she'd use in extremely subtle ways, preferably by messing with enemies' senses (I'd probably make her the best at genjutsu in the Konoha 12, since Sasuke prefers non-genjutsu Mangekyo powers for obvious personal reasons). And not something obvious like "I can't see!" More like things like messing with their equilibrium so they overbalance at a critical moment. She'd be tactical, but not like the other tactical fighters: rather than playing games with the terrain, misdirecting their attention, or using jutsu in really clever ways, she'd get in her enemy's head and mindf*ck them (both with words and jutsu).
Chouji Akimichi: Like the rest of his team, he'd get more team battles to make up for his shortcomings (relatively slow, most of his moves are very linear in their attack patterns, etc.). Most of his fights would involve others pinning an enemy in place so Chouji can whale on them hard. He would also master that jutsu his dad used to turn himself kaiju-sized, and hopefully combine it with something that can increase his toughness (probably some kind of earth ninjutsu to give him rock armor or something). Also, probably have him learn some earth ninjutsu to give him more defensive capabilities to make up for his lack of speed; basically turn him into a tank instead of the glass canon he was in, uh, canon.
Rock Lee: Not really much room for improvement, since he's taijutsu-only. Except maybe have him learn more styles so he's not stuck fighting with a Hard style against an opponent it's not as useful against, I guess, to give him more flexibility in a fight. He definitely needs to unlock the 7th Gate, instead of being stuck at the 6th like in canon. Now, if someone can actually beat into him the value of fighting with actual tactics and strategy in mind, that would be fantastic. I'm not saying he needs to be any kind of tactical genius, he just needs something in his playbook other than "Unlock first few Gates, rush forward and hit with Flashy Technique A. If this does not work, unlock more Gates, rush forward and hit with Flashy Technique B." At least throw in a feint every now and again, kid!
Neji Hyuuga: At the beginning, he'd be just like he is in canon. After getting Therapy no Jutsu'd, though, I think he'd diversify his skillset rather than continuing to rely almost solely on the Byakugan and Juuken-style taijutsu as a way of trying to find his own destiny outside of being "just" a Hyuuga from the Branch House. His drive and natural talent means he'd become above-average in pretty much everything (except taijutsu, obviously), making him an above-average jack of all trades (though not quite as much as Sakura, and more heavily geared towards frontline combat). He'd use those other skills when appropriate, but fighting like a Hyuuga would always be his go-to and feel the most "right" to him, to fit with his eventual acceptance of the Hyuuga name and his loyalty towards his clan, particularly Hinata.
Tenten: I typically like jack of all trades characters, but she really needs to specialize as well as diversify. Step One: Get a weapon that isn't mook tier, preferably one with a name (the Raijin no Ken from that filler arc would be ideal, but you'll probably have to settle for less). Step Two: Learn some nature manipulation and associated ninjutsu to use with it, preferably lightning nature. Step Three: Combine what you've gained from Steps One & Two, but also spam craploads of other weapons with your nature manipulation (start small with that until you build your reserves though, obviously; maybe one or two lightning weapons hidden in a barrage of easily-parried lesser ones). If there was an excuse for her to be able to learn some samurai arts that wasn't cringe-inducingly stupid, that would be fantastic. More likely though, her higher-tier stuff would involve becoming more skilled with seals and combining that with her weapons (if Naruto succeeds Jiraiya as a seal master, she'd be the 2nd best, but would probably be better than him in some areas). If she became a master blacksmith who is also a master of seals then she might be able to make a weapon on par with the Raijin no Ken and the Seven Swords of Mist.
