Rebuilding the Hyperbolic Time Chamber

Have Piccolo Jr. train under Mr. Popo alongside Goku, Yamcha, Krillin, and Puar. With Piccolo Jr.'s growth rate, he would quickly catch up to Goku's current progress, but defeating Goku was already impossible. Goku, Yamcha, Krillin, and Puar had already gained an initial grasp of the Ultimate Qi Training Technique, Eightfold Transformation Technique, and Sole Self, Myriad Phenomena Technique taught by He-El.