Description: This stage is between SSJ and SSJ 2. During this stage the Saiya-jin's muscles greatly increase in size. The Saiya-jin becomes very strong, but also very slow. Attacks would do a lot of damage, but it is unlikely to hit the opponent. When Goku and his son, Gohan were training in the Room of Gravity and Time during the Cell saga, Goku demonstrated this stage to Gohan, and told him that it was useless because of it's drawback of making a saiya-jin usually slow. This stage's disadvantage is demonstrated as Trunks fights Cell and is beaten.
Those who achieved this form: Goku, Future Trunks, Brolli, Vegeta
Description: This stage was first reached by Gohan while fighting Evil Cell in the Cell Game. This stage is very much like the first Super Saiya-jin stage, but of course much stronger. Occasionally, the Saiya-jin who is in the form has electricity going around his body and through it. That's how you can tell the difference between SSJ and SSJ2. Also a Saiya-jin level 2 has slightly longer hair. This level is more superior than ssj level 1 in terms of strength and speed. It is also triggered by extreme rage.
Those who achieved this form: Gohan, Goku, Vegeta, Brolli
Description: Goku is the first and only person besides Gotenks to reach this stage. It is one of the strongest forms in all of Dragonball. You can tell a Saiya-jin is SSJ 3 when they have gold hair like all the other forms before it, and their hair gets really long and full. Also, the Saiya-jin's eyebrows disappear. This level is only achieved through training. After training in Heaven during the period of time after the Cell saga, Goku learned how to transform to ssj3. This form brings more power and speed, but because it uses more energy, a saiya-jin can only stay in this form for a short period of time.
Those who achieved this form: Goku and Gotenks