Perhaps you should look into Dragon Ball Z? In Dragon Ball Z episode 289(Japanese), "Goodbye Majin Boo," Son Gokou throws the Genki Dama (Energy Ball) at Majin Boo, after Mr Boo and Satan move the Saiyajin prince out of ground zero. Majin Boo sends the Energy Ball back, because Son is out of energy, but, through Porunga and Dende, a wish is made, and Son is restored. He goes Super Saiyajin, and sends the Energy Ball BACK at Majin Boo, and then he speaks to Majin Boo of the battle they had had. Then, Son feeds most of his energy into the ball, and it discintegrates Majin Boo (not even leaving any cells), and before it explodes, destroys the Kaioushin spheres (like Kaiou-Sama's sphere, where he lived before it got blown up by Cell).
So, in Dragon Ball Z, Ascending during a Power Struggle was common. And you can only transform in a power struggle if you're perfect battle power, so, I think this is a feature that was left in.