Goku achieved this level in Other World as he could put unlimited energy into his transformation. Goku is first seen using this transformation against Vegeta during the Afterlife Saga. Once in this form, Goku was able to easily overpower Vegeta in his first form and fight more than evenly with SS4 despite a heavy ki drain taking its toll on him. It is said by Goku himself that if Goku had built up enough ki using Super Saiyan 3, he would have been able to defeat Vegeta in a flash. However, the transformation is extremely draining in terms of energy, as it cut Goku's time left on Earth from hours to a stated thirty minutes after performing the transformation for a short time. When attempting to gather enough ki to defeat Vegeta during their final battle, he was unable to sustain his acme after he attained it without the strain overcoming his living body, and soon reverted back to his base state.
After his victory he rested... while on Earth the Dragonballs are being used.I hope its something about Goku's revival!
Then unexpectedly they were revived and Vegeta learned the technique too.Vegeta challenges Goku.