Here are saiyan levels

Saiyan

Coming from Planet Vegeta, the Saiyans are a warrior race having different characteristics: black hair having always the same shape and length, tail, aggressive attitude and infinite appetite. Since they are not very clever, they exploit their victims technology (as that of Tsufurus)... they are always looking for new world to conquer ( and resell). They are very strong and, when they recover after deadly wounds, their power increases... this ability is called Zenkai Power.

Super Saiyan

An ancient legend tells that every 1000 years a special Saiyan born, having a huge power, called Super Saiyan. The first one who reaches this level is Goku, during the battle against Freeza, but then also the other Saiyans will reach it. The transformation into Super Saiyan is due to the rage that, exploding, makes the changing: the hair stands on end and become blond like the eyebrows, while the eyes turn green.
The ones who reach this level are: Son Goku, Future Trunks, Vegeta, Son Gohan, Brolly, Goten, Trunks, Vegitto, Gotenks and Gogeta.

Super Saiyan 2

This level is reached for the first time by Son Gohan, during the Cell Games. Gohan, pushed by Cell, lets himself completely go and the transformation takes place. His power increases drastically as his arrogance, the hair stands on end even more and his body is surrounded by lightnings.
Goku reaches this level in the other world, after the Cell Games, Vegeta, instead, during the Majin Buu saga, when he's under Babidi control.
The ones who reach this level are: Son Goku, Son Gohan, Vegeta and Vegitto.

Super Saiyan 3

Goku reaches this level in the other world and we see it for the first time during the fight against Fat Majin Buu. His hair is still blond, but this time they are very long while his eyebrows disappear. Also Gotenks, the fusion between Goten and Trunks, is able to reach this level during the training in the room of Spirit and Time.
The ones who reach this level are: Son Goku and Gotenks.

Super Saiyan 4

After he has turned Ohzaru Gold, Goku recovers his self control and his aspect returns "human": long black, hair, red hairs on his body and bloodshot eye... it's the Super Saiyan IV.

During the fight against Super Ishinlon, Vegeta will reach this level too, and will unite to Goku using the Fusion, giving birth to Gogeta Super Saiyan 4... the most powerful warrior in the whole Universe!

The ones who reach this level are: Son Goku, Vegeta and Gogeta.