For Goku and ssj3 level I feel like they could totally expand on ssj3 especially for Goku. I think it was alittle kicked to the side too easily and I always thought it was as awesome as Fusion or SSJG and a perfect enough boost for Goku like he was the one who could push Super Sayian forward and first in the show. I just feel SSJ3 could have more to it and it wasn't given enough support, interest, or training. I feel it could go higher if it was tested/trained more.
Even if it couldn't beet Byls or as Strong as SSJG which I'd just call Toriyama's idea for a SSJ fusion. Everything about SSJG seemed like fusion with a time limit and end. I say this as a fan of the story and of Goku I just seriously think they could do more.
I also realise by now SSJ3 was more of a gimick to further the show. If they didn't give Goku more power, he wouldn't have enough use in the Buu fight.
If you think about it the seires plot could just go in any direction but it was mostly just made up too.
So much of it I really want to make more serious because its not just some fantasy that was cool and just kicked ball it was awesome, more then any show at the time.
Alot of the ideas seem made on the spot and perhaps not with full interest in a serious plot. The ideas from this show just realy seemed awsome too much to just let go of because they gave ideas for so much, and if I may say mostly how a person not entirely human could be a hero for no reason but just to protect and get stronger. Thats always the story I just wanted and got from Dragonball and Goku.
This was just a rant about Goku and SSJ3 but I had more too say about the story as well. Im old enough and understand enough to say all of this as my respect for the show that was made my life more vivid to live.