I think there should be an extra kamehamehas. There should be a Chou- Kamehameha. It is a bigger kamehameha which does more damage, but I think it should be slower than the normal kamehameha, and not do as much damage as the final flash. All characters able to do kamehameha should be able to use...
I was thinking of maybe using a different animation after certain amout of charge up time, making it look more devastating.Showing when the chou version kicks-in indicated on the charge up bar.