Super Saiyan 2 is the second level of the Super Saiyan transformation, and exceeds the previous form's power by a larger amount than the Ascended Super Saiyan transformations. [Ascended Super Saiyan and Ultra Super Saiyan are in this category, in which the user buffs up.] In addition, it also outweighs a Mastered Super Saiyan's power output, but it barely shows.
So far, the SSJ2 transformation is unseen in Universe J-7. Although, it has been leaked into that it will make it's debut in either the PPnK Saga or Final Saga. As seen in the special short: " The Boys vs Manderin," the RowdyRuff Boys have mastered the SSJ2 Form nine months after the Final Saga's events and use it against Malachi's oldest son.
With respect to the highest level of Super Saiyan 1 (unmastered or mastered), it multiplies the user's power level by 5 times their Super Saiyan transformation. This means that if the Super Saiyan 1 is unmastered, it's merely 250, but if it's mastered, it's by 1500.