First of all, I don't see what is stopping the team from making the Spirit bomb the most powerfull attack in the game. The blast radius should be HUMUNGOUS and it should be damn near impossible to beat in a powerstruggle unless the defender is really far away, and has a ton of ki and is using a very powerfull attack (and has a high PL). Just leave the charge length the way it is, since it is so hard to get it fully charged and live anyways, it would make up for it being the most powerfull attack in the game. It should travel a little faster as well, since it is hella slow as of now (the alpha). Oh yeah, and the spirit bomb sprite should get a lot bigger.
I also think Goku should have kaioken, that is one of his trademark moves, so why doesn't he get it? There are so many ways this can be implemented. It could be another button just for goku to turn on the kaioken aura. The aura would obviously be red, and it would slowly drain health and rapidly drain ki. Attacks would be 3 times stronger and movement speed would be 3 times faster (Kaioken makes the user 3 times stronger and faster if im not mistaken, i forgot).
Another way for kaioken to work would be for it to be a charge attack. The longer you charge it the longer it lasts, and it would do the same thing as above. This would probably balance it out, since kaioken would be hella powerfull, but on the downside of it being a charge attack would mean players wouldn't be able to turn it on during a powerstruggle. I personally prefer the non-charge kaioken, but it should just drain ki like mad.
Goku, really needs another beam move too. When he turn SSJ, he should get his Chou Kamehameha. And when he is SSJ his spirit bomb shouldn't work, but I heard that that is already implemented.