"The Balance of Power" (超パワーのバランス Sūpā Pawā no Baransu, lit. "The Balance of Super Power") is the one hundred ninety third chapter of Dragon Ball Z and the three hundred eighty-seventh overall chapter of the Dragon Ball manga.
Future Trunks continues to push up his power, planning on showing his true power to Cell. Cell is certainly impressed by Trunks' magnificent power, even greater than his own, but assures Thunks that power isn't everything. Trunks calls Cell's statement a bluff and charges.
Inside the Hyperbolic Time Chamber, Gohan transforms into a Super Saiyan and flies around, throwing punches and kicks at the air. Goku, who is meditating nearby, is impressed with how fast Gohan has progressed. Gohan, in the meantime, is wondering why his dad has just been sitting there for so long. Gohan throws a few more kicks, then drops to the ground, reverting to his base form and gasping for air.
Goku then stands up, transforming into a Super Saiyan himself. He then begins to push himself harder, transforming into a Super Saiyan Second Grade. Gohan is amazed that Goku managed to surpass the Super Saiyan state, but Goku thinks he can push it even further, transforming into a Super Saiyan Third Grade. Gohan is really impressed by Goku's power, believing he can defeat Cell easily now.
However, back at the fight, one of the weaknesses of the Super Saiyan Third Grade form is being shown. For all his power, try as he might, Trunks can't manage to land a single blow on Cell, who is dodging all of Trunks' attacks with ease.
And Goku realizes this. He figures out that the Super Saiyan Third Grade form takes up too much energy and kills his speed, saying that all the power won't do any good if you can't hit who you're fighting. Goku comes up with a new plan, for him and Gohan to instead focus on mastering the basic Super Saiyan form.
Meanwhile, Trunks is baffled, wondering why he can't hit Cell despite all his power. Cell mocks him for relying only on brute force, then transforms into a Power Stressed form of his own, revealing that anyone can take on such a form.