To be honest about Goku mainly using Kamehameha as his beam attack there are words from Bruce Lee that i think are "I fear not the man who practiced ten thousand kicks once, but i fear the man who practiced one kick ten thousand times." and Goku practiced mostly Kamehameha, while Vegeta has things like Garlic Gun, Big Bang attack, Final Flash and other beams Goku's got only one he practiced.
some fusions were actually my prototypes for new character. in an attempt to save time and memory i'd try to make a new character by combining assests (smash bros does this all the time) . the android 17 and bojack fusion was an early attempt to make Kogu but the lead developer said "no he's perfect like that" so i never bothered to finish what i started. most of the charactes have similar origns. some where done at the lead guys request like Brolly shenron and buu whis
