They use Shunshin like every other ninja though, Lee himself said it takes a lot of stamina for his speed back in part 1, we know stamina is used to form chakra so taking a lot of stamina would be the same as using a lot of chakra. How else do you think they increase their speed when they use the gates which gives them more chakra?
Except Lee and Gai uses Shunshin just like other ninjas. Part 1 Lee said his high speed takes a lot of stamina and stamina is used to make chakra and chakra is focused into the feet to increase speed. Haku was Chunin level, Lee base is on a high Chunin level (like Haku low and Lee high) and Gai is Jounin, high speed ninjas can see Haku's movement in case you didn't know. Sasuke with a low level Sharingan was able to track Haku moves but his speed was still Genin level and he used Shinshun to increase it as shown here
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. Haku is actually slower in that pic, Edo's are weaker than when they're alive, Madara shown greater speed via Shunshin after he was revived than what Edo Madara shown.
He uses Shunshin which is a jutsu since you're focusing chakra into your feet to enhance your speed. Sasuke first uses it against Haku
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and every ninja uses it to enhance their speed above normal humans, even Lee and Gai.
He uses Shunshin to increase his speed
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. Minato, Itachi, Bee, Kakashi, Lee, Gai, and all other speedsters uses Shunshin to increase base speed or use another ninjutsu.
Minato was able to react to A's fastest speed so I'm pretty sure Minato is faster than him but that's using Shunshin.
Lee and Gai uses it to increase their speed as well you know. In part 1 Lee said his speed uses a lot of stamina, stamina is used to create chakra and chakra is used to increase speed for Shunshin. That's why they get faster when using the gates which gives them more chakra.
All of his speed feats are with Shunshin which put Itachi, Tobirama, Madara, and Minato (fastest) above him.
Minato reacted to A's fastest speed by reaching down to grab his kunai and tossing it up all while A's fist was in his face. A uses lightning armor to increase his speed which is a jutsu and it said no jutsu. All ninja uses ninjutsu to increase their speed such as Shunshin.
Itachi was gone long before Naruto got RM (Rikudo Mode). Also that's a failed point since Naruto made 12 clones prior to this so was at 1/13th the power and he was only in KM (Kyuubi Mode). Naruto wasn't using his speed at all in that fight, or at least not his faster speed since he uses Shunshin which focus chakra into the feet to increase his speed. He was more focus on talking to Itachi and Nagato then trying to beat them. So this isn't a speed feat for Itachi at all.
They focus chakra into their feet to increase their speed, still falls under ninjutsu as it does not go under genjutsu or taijutsu (hand to hand). Minato is the fastest with Shunshin, current Naruto may be faster but we only seen him use it once and Sasuke didn't do anything in ch. 700. Naruto has more chakra and his large chakra in KM/BM/RM is how he's so fast in those modes. In base its Minato as he has feats of being fast enough to react to A's fastest speed in his lightning armor (a jutsu).
That's Shunshin and with Shunshin Minato and Tobirama are faster but since no jutsus and in base, it's a hard call.
Gai uses Shunshin too tho, we don't know anyone's real speed without Shunshin. Chakra gives them the ability to do super human feats but without it they're basically regular humans for the most part.
Sharingan has nothing to do with speed. It's chakra control, you focus chakra into your feet to increase your speed. Sasuke did this against Haku before he awakened his Sharingan and Sakura does it against Ino. All ninjas pretty much does this to increase their speed.
Yet he's under A, Bee, Naruto, Tobirama, Minato, Madara, and Gai in Shunshin.
Probably because Shunshin depends on chakra control and how much chakra you focus in your feet. Naruto has the best chakra control as he gained knowledge of chakra with his RM and he shown masyery of many different types of chakra control and he has the most chakra in base at that point as well since he's 29-30 plus have Hashirama's cells which boost it even more. I believe Minato would be the fastest even now if he had lived at least until the War arc as he died before his prime.