I think all the SSJ levels need to be throughly explained from the top again...folks are highly confused:
Base - duh.
Oozaru/Great Ape - Transformation done by tailed Saiyans when looking upon a full moon or the artificial moon technique. 10x increase. Used by Goku, Gohan, and Vegeta in the canon. Given to Nappa, Radditz, King Vegeta, Bardock, and Selipa/Fasha in secondary sources.
Super Saiyan - The iconic original form first obtained by Goku in his fight with Freeza. Spiky gold hair, Green eyes, massive power boost. Stated in secondary sources as a 50x increase over base. Used by Goku, Gohan, Goten, Vegeta, Both Trunks, Gotenks, and Vegetto in the canon. Bardock, Brolly, Goku Jr. and Vegeta Jr. obtained it in secondary sources. Has 3 sub-forms that are basically, reallocation of the SSJ power and not new forms.
-Ultra Super Saiyan/Ascended Super Saiyan/Super Saiyan Grade 2 - First used by Vegeta to fight Semi-Perfect Cell. Increases the muscles size and makes the hair spikier. No speed loss was ever attributed to this form which is a common misconception. Used by Goku, Vegeta, and Trunks in the canon.
-Ultra Super Saiyan 2/Super Saiyan Grade 3 - First used by Future Trunks to fight Perfect Cell. Super Spiky hair and a massive muscle increase to the point of slowing down the users movements. Similar to the technique used by Master Roshi and Perfect Cell. Used by Goku and Trunks in the canon.
-Full Power Super Saiyan - First used by Goku to fight Perfect Cell at the Cell Games. The form is about removing the strain from maintaining the base SSJ form making it the users base so they don't have to waste energy transforming, powering up, or maintaining the form allowing more energy to be used for fighting. When in a relaxed state the users have light gold, almost blond hair. Used by Goku and Gohan in the canon
(No multipler has been given to the sub-forms in any secondary sources)
Super Saiyan 2 - First used by Gohan to fight Perfect Cell. Described by Goku as a Super Saiyan that's gone beyond a Super Saiyan. Much spikier hair and lightning around the user. Massive power gain. Secondary sources list it as a 2x increase from SSJ. Used by Goku, Gohan, and Vegeta in the canon. Gotenks, Future Trunks, Future Gohan obtain it in secondary sources.
Super Saiyan 3 - First used by Goku to fight Fat Buu. Described by Goku as a Super Saiyan that's gone beyond a Super Saiyan that's gone beyond a Super Saiyan. Hair grows down to ass level, eyebrows go away, and lightning surrounds the user. The greatest power increase among the canon Super Saiyan forms but excessively drains energy. Secondary sources list it as a 4x increase from SSJ2. Used by Goku and Gotenks in the canon. Vegeta, Brolly, Trunks, Future Gohan, and Gogeta obtain it in secondary sources.
***Since the Golden Ape & Super Saiyan 4 forms were deemed non-canon, they shall be omitted***
Super Saiyan God - The ritual needed to achieve the Super Saiyan God transformation. It requires five righteous Saiyans to perform and a sixth Saiyan to channel the ritual and ki into. When in this form, the Saiyan's general appearance remains unchanged with the exception of a few slight differences: the skin tone becomes darker; the hair loses any stray hair, lifts up slightly and gains the user's Super Saiyan form bangs, as well as adopts a red coloring; the Saiyan's eyes grow, becoming sharper and the irises become red; the overall body structure appears to become younger, thinner, and slightly taller; the aura becomes more explosive and flame-like in appearance. First achieved by Goku in the
Battle of the Gods film, then later by Vegeta.
Super Saiyan God Super Saiyan/Super Saiyan Blue - This form is nearly identical to the first Super Saiyan form, the only differences being that the hair is light blue in color while the overall body structure is thinner and slightly taller. Super Saiyan God Super Saiyan boasts a vibrant, fiery, electric blue aura, as opposed to the red-orange aura from Super Saiyan God. t is also said by both Goku and Vegeta that this form requires ki control and focus, so that means that this form has better ki control, unlike the Super Saiyan form. Because of its better ki control this form can be combined with the Kaio-ken. First achieved by Goku, and then by Vegeta.