Super Saiyan
Super Saiyan Stage 1
First attained by Goku during the Freeza fight when Krillin was killed by one of Freeza's Force Fields.
Usually only attained through extensive training and concentration, but most oftenly, as in Goku's case, it is accidentally attained when one experiences extreme anger. Only 2 other Saiyans had ever reached Super Saiyan Level before Goku. The first Saiyan who went Super Saiyan did it while in the Oozaru stage, making him completely insane. The other was Broly, the Lengendary Super Saiyan, who was actually BORN as a Super Saiyan. He was also completely insane, and only a necklece made by his father controlled his rage. Due to his being Legendary, Broly had a Power Level of 10,000 at birth, where as Goku's was 1. Upon reaching Super Saiyan, the individuals muscle mass becomes 3 to 4 times its normal size. Their strength and stamina also improve this much, and their hair stands on end and turns a brilliant golden. The person's regular Power Level usually triples.
Super Saiyan Stage 2
Gohan was the first to reach this stage when he fought Cell and his Junoirs.
Coupled with Gohan's power-driven emotions, he defeated Cell in 2 punches. There is little change between Super Saiyan and Super Saiyan 2. The individuals hair still stands on end, but more muscle, strength, and stamina.
Super Saiyan level 3
First attained by Goku during the Buu Battle.
The length of the individuals hair triples, or in other words, the hair goes Radditz on the person. The hair is more flexible, but still pretty stiff, except for two strands up front that 'hook' inward. And of course, more muscles, strength, and stamina!
Super Saiyan Level 4
Many people do not consider this class to be Super Saiyan, due to the lack of bright gold hair. Goku became Super Goku Level 4 by transforming an additional time after he transformed into the Golden Oozaru monkey. He did this by looking at the Earth, while he was on the moon (opposite of usual way to become an oozru). Then, when he returned to normail, he was SS4. The character grows a tail, and is covered in red hair (except for the bare, muscular chest). Their hair gets shorter, but black, and all Ki attacks require very little effort.
Saiyan Oozaru Form
A Saiyan looks at heavenly body (especially the full moon) and he immediately transforms into a 100ft tall monkey whose power is about 10X his regular power.
Golden Oozaru Form
Goku accidentaly became this for of Oozaru by looking at the Earth while on the moon. More powerful than the first form. By about 15X more powerful.
More in depth
SAIYAJIN!
In the very early stage of a SJ, they all have black hair and they look just like ordinary people. They gain their power level by training, fighting and improving. The maximum power level can be gained by an exceptionly powerful SJ is around 200,000 or 300,000.
Advantage: None
Disadvantage: None
Interesting Fact: Trunks/Future Trunks is the only Sayian who hasn't got black hair. This is because he is mixed. Goku was born to be a much inferior Saiyan Jin, with a power level of 2.
Reacheable by: All saiyans.
SUPER SAIYANJIN (SSJ)
The first Super Saiyan Jin appeared in the DragonBall series, there Goku was fighting against Freezer. To transform into a Super Sayian Jin, the Saiyan must be able to build up the anger inside. Let the anger to increase the desire of revenge therefore pushing the Sayian Jin's power level suprassing the maximum limit. If the process is successful, the Sayian should have gold hair which sticks up and eyes turning green. They also have a glow of golden light wraps around the Sayianjin. As a Super Sayianjin, it increases the power, speed and agility. This was how Goku killed Freeza in the DragonBall Z series.
Advantage: It increase the overall power.
Disadantage: None
Interesting Facts: Goku was the first Earth-raised SJ to become a SSJ, and maybe the first SJ other than Broly (The ancient legenday SJ). Vegeta got jealous seeing Goku as SSJ, therefore he quickly went back to martial art training which made him the second SJ to turn into a SSJ. Goten is the first ever SJ who has the natural ability to turn into a SSJ, with out pushing himself to the limit. Gohan turned into a SSJ by training with his father Goku during the battle with Cell. In this stage Goku can not use the Kaio Ken attack. Gohan's death by Androides 18 and 16 triggered young Trunks' anger and the desire for revenge, hence transformed Trunks into SSJ.
Reacheable by: All the saiyans. Except Pan. Others that we never see in SSJ is because thay never had what it takes!
SUPER SAIYANJIN 2 (SSJ2)
Super Sayian Jin Stage 2. Again, to get to this stage, a SSJ must be able to push past his own maximum limit. To get to this process is much easier than transformation from SJ to SSJ. Just by working extra hard, any SSJ can get to this level. A successful transformation will result in gold solidified hair which is split into pieces of triangular strips. The hair still sticks up and the glow of golden light is still around the SJ.
Advantage: As a SSJ2, they have the abilty to adjust their strength/speed/agility. More experienced fighters such as Vegeta and Goku, they know how to balance up to make them well adjusted. If successful, it can also result in increasing more strength/speed/agility.
Disadvantage: If one part of the power go up the other two have to go down. For example, if a SJ chooses to have more strength, he/she has to sacrifice speed and agailty. Simple as that.
Interesting Facts: Vegeta was the first to be successful in adjusting his strength/speed/agility. He firstly transformed himself into SSJ2 form, and adjusted his strength/speed/agility while he underwent martial art training. This sort of training had given Vegeta an extra boost in every part of his battle. The results was clear, he had no trouble beating up Cell and got him packing to get more training. This transformation by Vegeta was well superior, and by honoring his own success, he named this transformation as Super Vegeta. In this stage Goku can not use the Kaio Ken attack. Future Trunks was also quite successful in building up his strength/speed/agility. However, he concentrated too much on his power and left out the importance of speed and agility. While fighting cell, he wanted to show off his training success and increased his power by a few factors. True, his power was immensely great, but he didn't realise his speed and agility was letting him down. Cell then told him that his transformation of increasing strength and decreasing speed was the wrong transformation and that will only get him killed at the end.
Reacheable by: Goku, Vegeta, Gohan, Trunks and I think Vegeto and Gogeta..
SUPER SAIYAN JIN 3 (SSJ3)
This is once again, the next stage from a SSJ2, or possibly the final transformation. By expanding the power (similar to the transformation from SJ to SSJ) to get to this stage. However, getting into stage isn't easy, it requires MUCH MORE strength to transform from SSJ2 to SSJ3. The only difference between a SSJ2 and SSJ3 is that SSJ3 has much longer hair and a much more vicious look. The eyebrows are gone might be a result of the vicious look.
Advantage: The SSJ3 has much greater strength/speed/agility. Which it makes the SJ almost complete.
Disadvantage: Since a SSJ3 is much more powerful, it uses up more strength too. A SSJ3 fighter can fight for a while, but he/she gets tired very quickly too. It is know that resting will not build up strength, it will lose strength.
Interesting Facts: Goku is the only SJ to get to this stage, apart from Brolly (I guess Brolly has the ability too). Gotenks is the first combined SJ to get to this stage. In this stage Goku can not use the Kaio Ken attack.
Reacheable by: Goku and Gotenks.
SUPER SAIYAN JIN 4 (SSJ4)
Once again, the next stage from a SSJ3, to SSJ4 the final transformation. By expanding the power (similar to the transformation from SJ to SSJ) to get to this stage. However, getting into stage isn't easy, it requires ALL THE strength to transform from SSJ3 to SSJ4. The only difference between a SSJ3 and SSJ4 is that SSJ4 has long black hair and, cloths change and, no shirt, also a much much more vicious look. The eyebrows grow back (don't ask me why) and guess what he grows back.. a long red tail (can't find out why).
Advantage: The SSJ4 has the greatest strength/speed/agility. Which it makes the SJ a true complete fighter.
Disadvantage: Since a SSJ4 is the most powerful, it uses up all the strength too. A SSJ4 fighter can fight for a while, but he/she gets tired very quickly too. It is known that resting will not build up strength, it will lose strength.
Interesting Facts: Goku can not use the Kaio Ken attack.
Reacheable by: Goku, Vegeta and Gogeta.
OOZARU
A transformation process of a saiyan by just looking at a full moon. It is another way to gain power. By looking at a full moon will transform them into a giant monsterous ape. They can do this only if they a tail at the present moment. If the tail is cut then the Saiyan will be transformed back into his normal form. An artifisial moon light can be also replaced in order to transform when there is no moon. However you need a lot of power to produse it.
Advantage: The Oozaru stage makes a saiyan's power 10 times more. It's stronger than his normal form, but not as strong as SSJ.
Disadvantage: Since the saiyans become large apes, It's a little diffecult to control their body. Also they cant control their actions, unless of course they train, or being guided by someone.
Interesting Facts: Trunks did not have a tail. Also Goku's tail was removed by Kami Sama and it never grew again by it's self. Other saiyans like Gohan's and Vegeta's grew by it's self after being removed. It seems that Kami Sama, found a way so that it would grow again.
Reacheable by: All saiyans.
GOLDEN OOZARU
A transformation process of a saiyan by just looking at a full Earth. It is another way to gain power. By looking at a full Earth will transform them into a giant monsterous ape. It looks just like Oozaru, but with golden fur.
Advantage: It is a little more powerful than SSJ3.
Disadvantage: Can not be controlled.
Interesting Facts: This transformation does not require a tail.
Reacheable by: Goku and Vegeta.
