My idea is to disable powering up the energy but swooping and attacks etc should take FAAAAAAR more little energy. I wanna say that we dont see characters regaining theyre energy in the series except goku fighting kid buu but thats a "special case". You could only regain energy by not fighting. And as i said attacks, energy beams etc would take lot lot little energy so we would have enough energy only if we fight very very much and do some kamehameha for example we would have energy low.