Goku looked at his small hands and then up at Uub. The training was over, but a new, more dangerous journey had just begun.
Before Uub could answer, a pillar of crimson light erupted from the temple. The sky didn't turn black as it did with Shenron; it turned a bruised, electric purple. The Earth began to tremble, not from a physical blow, but from a cosmic imbalance. Goku looked at his small hands and then up at Uub
Goku wiped sweat from his brow, his orange gi tattered but his grin as wide as ever. "You’ve grown, Uub. Your control over that energy... it’s unlike anything I’ve seen since, well, since I fought Buu." The sky didn't turn black as it did
Here is a short story based on that specific transition and the start of the GT era: The Weight of a Promise "You’ve grown, Uub
Inside the ancient halls of the Lookout, a shadow moved. Emperor Pilaf, older but no wiser, had finally breached the inner sanctum where the Black Star Dragon Balls were kept—relics forgotten by time and guarded by the late Kami.