Part of the reason both Sakura and Tsunade are underrated by the fandom is tied to the despise shounen fanboys have towards healers. They only care about flashy powers and explosions and ignore healing because they find it "boring". However, I do think Kishimoto wasted a lot opportunities of using medical ninjutsu in battles. Medical ninjutsu can be effortless deadly, as Kabuto shown many times. Also, the immense network healing performed by both Sakura and Tsunade through Katsuyu, if they change the healing aspects of the chakra, they can turn a massive amount healing into a dreadful weapon in large scale.
Medical ninjutsu could've make interesting additions to elemental ninjutsu(water style) and even genjutsu, since it's all about using chakra control to control another person's body.
Any thoughts or headcanons? ❤️
Dude, you’re so speaking my language. So, I’m going to go through all of this because I actually have a l o t of ideas I’ve come up with for my own but I want to go through this piece by piece because there’s a lot more that can be done with not just medical ninjutsu, but the chakra control needed to perform it that’s also needed for genjutsu and chakra-enhanced strength (and the Byakugo) that go hand-in-hand.
Biomedical knowledge: Though not ninjutsu in and of itself, the knowledge a med-nin has to learn grants exhaustive knowledge of the human body that Sakura is quite gifted at. Yes, it’s obviously very much needed for healing, however... such knowledge could be used to a combat med-nin’s advantage like pressure points used offensively, quickly identifying weak points on an attacker’s body, and on. It’s actually called Kyusho in martial arts, so it could be a totally valid thing to learn and use offensively!
Offensive agents: Alright, clumsy wording, but with this I mean tactics such as poisons and antidotes, sleeping agents, tranquilizers, and so on. We all know that Sakura surpassed Tsunade in this area, but it’s something massively overlooked and could’ve been used much, much more often--especially since I highly doubt Sakura and Tsunade just punch their way out of everything. With these, Sakura and Tsunade could’ve (and should’ve!) been highly talented at covert missions. After all, what med-nin wouldn’t be superb as a spy? Nono Yakushi and Kabuto were renowned as spies in canon, so why not Tsunade and Sakura? Paired with their legendary repertoire with poisons, antidotes, tranquillizers, and more, I have no doubt they could’ve been even better.
Genjutsu-types: Now, this is more a Sakura-thing than Tsunade (since I don’t remember any instances of Tsunade being tied with genjutsu prowess), but aside from Sakura’s peerless and canon ability to identify and nullify genjutsu being used on her to the point of immunity, there’s a concept I like exploring with her as a “genjutsu-type”, a headcanoned classification up with others like Med-nin, Sensor-type, etc. This brilliant meta explores some possibilities, but two I like to add are Inner Sakura as a Yin Release-construct capable of breaking mind control and genjutsu (aside from its game-based abilities to manifest as a physical cloneto cast genjutsu, be used in taijutsu, etc.) as well as actually casting genjutsu.
- Manipulating chakra: This is another headcanoned ability I have comes from this same meta and it’s how a genjutsu user can manipulate chakra flow to cast illusions. Some uses I’ve come up with are the ability to prevent chakra from being molded to nullify ninjutsu from being casted, as well as a future expansion where a Genjutsu-type can manipulate chakra in the body to cause mayhem (like inducing a heart attack, stunting breathing, messing with the brain on a biochemical level, etc.) without ever making physical contact with the victim. As genjutsu demands manipulating yourself or another’s chakra flow to cast or break it to begin with, a midway point could mean a genjutsu-type like Sakura could pair it with her extensive medical knowledge and cause some real damage.
Deadly medical ninjutsu: As we all know, Sakura has utilized medical ninjutsu offensively when she paired it with CES to stunt Kido’s healing factor in Sakura Hiden. However, going on what you said here, I have some more uses in mind: The Immense Network Healing is used to channel chakra to those connected to Katsuyu’s clones, but never specified that it can circulate only healing chakra, now does it? And, like you said, healing chakra can be deadly if too much if flooded into the body, the recipient can become comatose.
- Chakra scalpel: As you state, Chakra Scalpels can absolutely be used to deadly effect offensively, and with Tsunade and Sakura’s level of chakra control, who’s to say that they couldn’t master it even further.
- Deadly Illness Extraction Technique: Now, while we’re aware that this technique is used to both diagnose and extract poisons, what if it did something else? Or the opposite? Like spreading a poison or tranquilizer in someone’s body to hasten the effects; like, a tranquilizer that takes minutes to take effect could only need a few seconds if the user is skilled enough. Or, finding weaknesses in the body to exploit?
- Healing Power Alteration Technique: Now, while this technique has only been named, my own headcanon is that it’s used to cause cell death. Benignly, this can kill off cancerous cells, stop the spread of infection, necrosis so that it can’t spread further, etc. Offensively, with an increased amount of chakra can cause flash mummification of whole limbs to an entire person in just seconds.
Chakra control & Chakra-enhanced strength: Now, while this is entirely headcanon, we all know that in Sakura Hiden, she combined increased chakra control to break herself from restraints, flood chakra in areas to withstand harsh blows, halt and nullify elemental ninjutsu, and more. By adulthood, this evolved into the creation of a literal chakra radar. However, there’s even more areas that require advanced chakra control for the transformation and modification of techniques I’ve come up with that combine with these abilities.
- Shape Transformation: An advanced form of chakra control that involves controlling the form, movement, and potency of one's chakra, determining the size, range, and purpose of a technique. Now, factoring this in with CES, what if Sakura could alter the shape of her blows? Instead of just unleashing bursts of chakra to decimate or pulverize, what if she shaped it into blades or long releases of chakra to impale with? I have more here in a body of techniques I created.
- Nature Transformation: This one, of course, is the second part of ninjutsu modification I combine with CES in my headcanon wherein Sakura channels Earth, Fire, or Lightning Releases into her blows to increase how devastating they can become. Fire Release to superheat the chakra Sakura expels to the point that it can catch fire and scorch its targets. Earth Release to shape and conduct how CES is performed, like creating sinkholes, deliberately shaped fissures, impact depth and radius, and so on. Lightning Release (that she has in the games) paired with Shape Transformation to increase the cutting power of her blows.
- Chakra flow: A nature transformation type that pairs with the former, as stated above, chakra flow can be used to enhance the properties of weapons... however, they can also be augmented with the user’s body. As Sakura already has the ability to channel chakra throughout her body, paired with elemental ninjutsu could enhance how she fights. Like the Raikage’s Lightning Mode, I imagine a watered down version where Sakura uses it to stimulate her nervous system to drastically increase her reaction time, speed, and defensive power. Like Kakuzu’s Earth Spear, Earth Release flowed throughout her body can bolster her defense and increase the potency of her physical attacks. Lastly, Water Release can boost her physical defense like armor. (More on these two can be found here!)
Tenketsu control: While it’s stated that only the Hyuga naturally are able to innately release chakra from any tenketsu on their body, why not Sakura who’s stated to be able to circulate chakra anywhere through her body? After all, given the fact that Sakura has surpassed Tsunade in ability as a med-nin, it’s not beyond the possibility of belief that she could memorize the location of her body’s tenketsu and learn how to manipulate chakra accordingly.
Body seals: What we come to understand of seals like the Byakugo are that they can store chakra on a point on the body. Now, in the realm of medical ninjutsu, Sakura has also proved capable of using fuinjutsu to create traps that can activate via a seal on the body. But, in regards to your ideas, what if Sakura could do other things like create body seals that could release jutsu? Genjutsu, poisons/tranquilizers, triggers to activate traps, and so on.
- Senjutsu & seals: Now, this is another original idea of mine, but what about a seal that could store sage chakra to activate Sage Mode? Something that’s been established is that a Byakugo user can utilize the chakra stored without fully releasing the seal. My thinking is that Sakura can store sage chakra in a seal, but create a feedback loop with the Byakugo to constantly knead it with normal chakra while releasing minute amounts through her tenketsu to keep her from turning to stone? Given the fact that Sakura innovated the Byakugo storage process to divert some chakra back into her own stores, this could be something well within the realm of possibility.
Body augmentations: Another possibility is the notion that Sakura could feasibly experiment on herself or others to enhance her prowess. The most visible times we see this in the manga is when Kabuto experimented on both Madara and himself to give them both a significant boost in power based on Kabuto’s esteemed medical knowledge and what was done with Orochimaru. Both were so significant that Madara was nearly unbeatable and Kabuto was able to attain Snake Sage Mode. Imagine what someone with Sakura’s experience could do?
In any case, thank for the ask and I hope these are to your liking! All I ask is you give me credit if you use these, thank you.~