Okay, so for starters, dont use Wikipedia or other sites. I can tell you didnt write parts of it due to the obvious special characters here because I severely doubt most Sharingan Sensei cover all of this. You guys tried to throw so much information together to answer it quickly and you almost missed the questions I asked. Not saying it is wrong or anything but it defeats the purpose of me asking what you know if you are going to copy information from other sources. That said, let's start. I'll break your posts into sections to make it easier to reply to.
OK so the Sharingan (写輪眼, Copy Wheel Eye) is the Kekkei Genkai of the Uchiha clan. This blood limit is a Dōjutsu (Eye Technique) which allows the clansmen enhanced perception, able to read Ninjutsu, Taijutsu, and Genjutsu. However, the Sharingan is not a must and not every Uchiha unlocks it. This is because the Sharingan is considered a want and not a need, a simple wish won't grant the Uchiha the power- he needs to yearn the power just as much as he years air to breathe. It consists of two main roles/features; Dōsatsugan (The eye of Insight) and Saimingan (The eye of Hypnotism). The first, Dōsatsugan, allows the user to see chakra, in different colors and patterns as well as insane cognition when it comes on to fast moving things or people, the user is also able to copy any Ninjutsu, Taijutsu, or Genjutsu encountered that doesn't revolve around a Kekkei Genkai. This also means that the user can see different chakra types and react accordingly, even when it's being molded in the target's body an Uchiha will be able to see it, this puts them a very well placed advantage capable of countering a technique before it is even released. The second, Saimingan, allows the casting of illusion type techniques through mere eye contact. These can span from petty illusions ((Magen: Kyouten Chiten) - Demonic Illusion: Heaven And Earth Change) to serious toll takers like Tsukuyomi. That being said the eyes of each Uchiha is connected to the brain via the optic nerve but also a special branch of chakra pathways for each eye. Upon emotional or physical trauma a wave of chakra is pulsed through these channels into the eye and births either a one tomoe, two tomoe, three tomoe, or even the rarity of the Mangekyō Sharingan. As seen with both Madara Uchiha and Sasuke Uchiha, the Mangekyō Sharingan can later evolve into an Eternal Mangekyō Sharingan, with the acquisition of a siblings Mangekyō Sharingan after one has lost the light from theirs. Later on in the manga, and series Madara is later shown to evolve even farther into the Rinnegan after acquiring Senju DNA from his mortal enemy, Hashirama.
For the most part, all of this is right, but we will touch more specifically about these colored parts later.
One Tomoe
This is the first variation of a partially developed Sharingan eye. The clan members pupil will turn red and develop one of the wheel swirls. User can read low ranked Taijutsu moves and counter almost naturally, can sense low ranked genjutsu, and can read fast movement not achievable by the normal eye.
Two Tomoe
Increased perception than before, almost an exponential increase. As seen when Sasuke had trouble keeping up with Fox Cloak Naruto with his single tomoe but as soon as it evolved he was able to clearly see the movements of his rival albeit they were insanely fast.
Three Tomoe
The pinnacle for most clansmen. This allows top notch cognition, and perception on the Uchiha's side. He is also able to utilize the Saimingan side of the Sharingan, being able to cast illusions on the opponent through eye contact or general proximity- as seen with Shisui's Kotoamatsukami (even though it's a MS technique). This is also were the user gains the ability to copy moves with pinpoint accuracy.
Mangekyō
Attained through sheer mastery of the Sharingan in it's 3T stage. This grants the user unparalleled ocular prowess as well as some Uchiha gain the access to the 3 spiritual weapons of the heavens; Susanoo (God of The Storm, an ethereal warrior to protect the user in times of great need), Amaterasu (Goddess of The Sun, Divine Light and sister of Susanoo, grants the user eternal black flames casting anywhere he looks that only finishes burning when its target is no more), and Tsukuyomi (God of the Moon, an illusion which simulates true horror within the opponent's mind which seems to ignore the laws of time and physics). In addition to these the user is also granted, through strenuous work, Izanami and Izanagi. The first is the power to decide fate, through physical sensations shared by the user and the opponent which traps them in a Genjutsu that forces them to accept their true fate or loop forever. The second is the ability to bend fate, by turning reality into a Genjutsu and escaping death or a predicament. Both these techniques are considered Kinjutsu and always end in the loss of sight of the eye used.
Eternal Mangekyō
With the same abilities as the Mangekyō, only that these eyes will never lose their light no matter how stressed they become. They only get deactivated. It is unknown whether or not this happens if the user uses Izanami or Izanagi however. In addition, the user allegedly gains access to the Perfect Susanoo, who stands thousands of meters tall with completed legs and armor, shattering mountains and shaping landscapes in it's wake.
Good, but you failed to speak about how any of this relates to the RP. The 3 Primary Stages of the Sharingan are 1Tomoe, 2 Tomoe and a Fully Matured 3 Tomoe Sharingan. The notable difference between these 3 stages is first the obvious growth of an additional tomoe, but performance wise, each level increases the "power" and usefulness of each basic ability the Sharingan grants. These primary abilities relate to tracking and visual perception. It increases almost in a stepladder, going up as you progress. Upon reaching a Fully Matured Sharingan, the ability to cast Sharingan Genjutsu is granted, increasing the connection to Yin Release.
These eyes can be furthered progressed, though at dangerous and fatal consequences. Witnessing the death of a loved one at your hand or another's, the Mangekyou Sharingan awakens, bestowing several abilities of their own. Each Uchiha has two techniques unique to them, though this was originally stated that each Uchiha with MS must awaken Amaterasu and Tsukiyomi before they are able to activate Susano'o. Obito had two different versions of Kamui in each eye for example and Itachi had Tsukiyomi and Amaterasu. Upon awakening of the Susano'o, the user gains a powerful guardian that is able to be manifested around him for protection. However, as great as the MS is, it comes with it's own flaws. It's power considered incomplete, after overuse of it's abilities, the user runs the risk of becoming blind, making their treasured eyes useless. In order to correct this, the user is able to take a sibling's eyes who also has MS and place them in your own, gaining access to what is called the Eternal Mangekyou Sharingan.
The EMS is the perfected version of the Sharingan, or so we thought. It allows the user the ability to use all of the MS abilities but at a stronger level and at a much lesser level of stress on the body. Izanagi still affects these eyes, case in point being when Madara used it against Hashirama. It also increases the power of the Complete Body-Susano'o, as it was officially named in the 4th Databook. It was also revealed there that Madara alonne has a "Perfect Susano'o", due to his mastery of the jutsu. This means that while Sasuke and Obito/Kakashi were able to create a Complete Body-Susano'o, only Madara's version is considered Perfect for some reason, presumably because of strength. In Madara's case, it also allowed him the ability to control Tailed Beasts, turning them into slaves themself.
Further beyond this is the Rinnegan, which is not exactly a Sharingan evolution as well as the Rinne Sharingan, the original Doujutsu.
The rest is fine.
Rinnegan
>Be a badass
>Bite a Senju
>Obtain greatness.[/QUOTE]
I apologise for the late reply. School work and stuff.
To answer the first questions.
First, I'd like to introduce the sharingan, the sharingan literally means copy wheel eye and its the kekkei genkai of the uchiha clan. I can go into the origin of the sharingan which comes from the rinne sharingan which is a mix/breed between the sharingan and the rinnegan, eventually evolution took place and it was disintegrated to form plane crimson red eyes and black tomoes of 3(max), which will then be regarded as one of the 3 main dojutsu.
Second, i'll go into it's abilities. The sharingan has two core abilities, the eyes of insight and the eye of hypnotism. I'll begin with "the eye of insight", its rudimentary abilities are to see chakra flow(similar to the byakugan) and give colour to them. Once a colour is attached to chakra, the wielder of a sharingan can then differentiate between various form of chakra and further more identifying them as chakra signatures specific to a being because of the colour and form attached to that being. Because of their ability to see chakra flow they are well capable of deducing if/when someone is under genjutsu(an illusion) because of the anomaly of the routine chakra flow. To further the abilities of "the eyes of insight", is the ken sight, which enables the user to comprehend barely noticeable details, mimic slight body movements and see through some vision impairments(note a fog created by another shinobi would render a sharingan user confused/blind of the shinobi, although they possess a unique ability to different chakra signature by giving it colour, this ability also makes them vulnerable if I may say. If another shinobi uses the fog/mist technique, the sharingan will view the fog as the shinobi's chakra colour signature, and as the fog spreads out that will be all the sharingan would see; the shinobi's chakra signature), and as the sharingan develops this ability of insight improves, the user does not just become aware of subtle things but can track things that are moving fast, Being able to track fast moving objects opens the copying ability because whoever or whatever the sharigan is put against appear to be moving slow, further more allowing the sharingan wielder to memorise the person or technique(genjutsu,taijutsu and ninjutsu) and then use the technique as if it were theirs.
How does the copying work?...well because of the sharingans ability to see the flow of chakra and also mimic a persons movements, the user can mimic the opponents hand seals, and through their ability to see chakra flow they can gauge the amount of chakra required to exhibit the technique their opponent uses/used. Because they are gauging the amount of chakra needed they can copy any technique(apart form other kekkei genkai's and summons unless they have signed it) with near absolute accuracy. This particular ability then opens up more and give the user the ability to predict their opponents next move, in other words they can predict their opponents next action and react accordingly. Although this power is great but if the user isnt well versed in training then their body cannot react accordingly hence the saying with great power comes great responsibility.
Now moving on to "the eye of hypnotism", this ability grants the user to induce illusions in their opponent, causing him to see what they want or even act how they want. This ability stretches far as it doesn't not only work on human but also beasts and summons, this ability grants the user to makes illusions which can paralyse, induce sleep, break another sharingan user from genjutsu or even make the target temporarily insane through playing gruesome images in the head of the victim, maybe reminding them of the evil deeds they had done in their past. The "eye of hypnotism" has an almost unlimited potential but it is all based on the sharingan wielder, how versed they are in the use of genjutsu.
The Differences between each Tomoe:
As I said in my earlier description, the sharingan develops, this development is displayed through the eyes by gaining a tomoe in both eyes as the user becomes much more competent with the sharingan. But first i'll talk about how the sharingan is unlocked before the gaining of tomoes.
The uchiha eyes are naturally black in colour and that's all it'll ever be unless that uchiha undergoes specific scenarios to gain the sharingan. To unlock the sharingan the user has to know or possess a strong emotion towards something or someone, then when the scene of losing that loved person or object happens or experience a terrifying , stressful and life threatening situation. When either of this happens the brain of an uchiha releases a special kind of chakra towards the optical nerves causing the eyes to transit into the sharingan(note: when the sharingan is first awakened, it has a different amount of tomoe surrounding the central pupil and this varies between users).
One Tomoe:
In this stage the users eyes gain one curved black pupil surrounding the main pupil in his/her red eyes. The user can see the flow of chakra, can also identify someone(himself and others) as a victim of genjutsu, can easily break out of a low ranked genjutsu. The users can track speed better than the normal eye and also ninjutsu. Allowing them to react to attacks accordingly if their body can keep up.
Second Tomoe:
In this stage, a second tomoe emerges in the users eyes making them two, it also gains the abilities its predecessor has or had and makes them better. It can track faster speed than normal allowing the user to analyse them and then mimic them. They can to some extent predict some ninjutsu techniques. The user can then exit visual genjutsu that are a littler higher ranked.
Third Tomoe:
In this stage, a third and final tomoe takes place in the users eyes. It has the generic abilities but highly developed and then can perceive motions, predict and as well as copy them. They can keep up with high speeds, break higher ranked visual genjutsu and induce illusions.
Mangekyo Sharingan:
To achieve this ability one has to suffer the trauma witnessed from losing the death of a loved one first hand or through sheer will and mastery of the 3T the user will then gain the MS. The appearance of the MS varies from user but all MS resembles pinwheels. The MS carries the other generic abilities of the various stages of sharigan(1-3tomoe) and also access to much more powerful techniques like Susanoo, Amaterasu, Tsukuyomi and others. Extensive use of this abilities would cause the user to get blind. Though with each of the various abilities the user eyes slowly withers until it cannot see anymore.
Eternal Mangekyou sharingan:
The ability is gotten through the transplant of a close relative own eyes into the uchiha. The user also gains all generic abilities at their best use. Then the user cannot loose the light in their eyes.
There are other variations higher than the sharingan, like the rinnegan and rinne sharingan. I would divulge such info cause it seems irrelevant at now.
See portion above.
How do they assist with elemental ninjutsu?
Urm....although i'm not sure if I understand your question but i'll try and answer.
The sharingan helps to identify the nature of an element. When an opponent uses an elemental based ninjutsu techniques the sharingan allows its user to identify the element, in other to counter it. This is not the only way the sharingan can help. In other to copy the technique and use it before the opponent can, the wielder will not only have to read the hand seals but also know the element in use and the sharingan aids in identifying the element. Either through its fluidity (water), through its breezy nature(wind), rapid friction(lightning), sizzling nature(fire) etc.
I guess that's all.
Good attempt, but you are incorrect in parts. First, the Sharingan can't tell what element is being used. It allows you to see chakra flow. When seeing this chakra flow, should a foe begin an attack using elemental affinities, your Sharingan will be able to see a spike in this chakra flow and can see this flow become Nature Manipulated. Depending on which nature is applied, you might observe different changes with the Sharingan. Water chakra generally flows fluidly, much like water itself, yielding and bending along the body. Fire chakra resembles that of heat waves, waving intense motions, almost like a gas. Lightning chakra is identifiable by it's erratic and random movements, portions of it's flow appearing to break off in tangents everywhere. Earth chakra becomes denser, more compact which makes it appear as a heavy gathering of chakra due to it's natural denseness. These different flows can be observed more clearly with each level of the Sharingan.
Since we have stumbled on Chakra Flow and observation, I ask my next group of questions: What differs with the Sharingan's ability to see chakra flow vs the Byakugan's ability to see chakra flow? The Byakugan is known to have what could be called telescopic sight, but the Sharingan does as well, on a lesser scale. What does this mean? What level of clarity and perception does the Sharingan have against objects filled with Sharingan? Meaning, how well does the Sharingan pierce if an object of chakra is in front of it?