When: Goku got so angry at Freeza for killin Krillin, that he did not wanted no one else to get hurt and "puff" he reaches this stage of SSJ1.
And in movie #4 Goku also reached this transformation when he was fighting with Lord Slug.
Who else: Gohan, Goten, Vegeta, Future Trunks, Trunks (present)
Physical description: the hair grows and is blonde. Their muscle mass increases. Sometimes a yellow aura or lightning is accompanied by this transformation.
When: In the Cell Saga, when Cell pushed Gohan to his limits, Gohan reached this level. This was because Cell Jr. were beating the Z Warriors to a point that Gohan couldn't take it anymore.
And also in movie # 9, Gohan and Goku reached this level to kill Boujack and his crew.
Who else: Goku, Vegeta, Trunks
Physical description: Greater muscle mass than SSJ1, and a few more inches of blond hair. Occasionally accompanied by zapping lightning.
When: In the Majin Buu saga. Goku learned this technique in the afterlife and used it to fight Buu.
Also in movie #12 Goku transformed to destroy Janeba,
We can also see this transformation in Dragon Ball GT, but since Goku was a small kid his body had a slack of strength
Who else: Gotenks
Physical Description: His hair grows 4 and half feet, still blond hair, larger muscle mass, his look is more menacing and he does not have no eyebrows.
When: This is only shown in DBGT series.We see it when he is fighting with Bebi.
In this stage Goku is almost Godlike, he can use "Times 10 Kamehameha" with no problem.
Who else: Vegeta, but only with a machine that Bulma did for him, cause he could not reach this stage.
