As for leveling up, it seems Goku has hit a wall. The little meter doesn't go up anymore. I keep getting the experience, but it's filled up in yellow now, and I can't do the "Skiiiiiiiiiill Uuuuuuuuuup!" thing in the character upgrade menu. I'm positive you can do more, because the little "choose-your-own-adventure" (hehe) path still has more options down to go.
You have to use that yellow bar in order to fill it again and again...
You can use it to get other characters skills.
You should notice that there is a third option available at the customize screen.
If you select it, you will be allowed to get some other skill from a certain character (one that you have already created a file and started using it for powering up).
Another thing that's irritating me is that other than the new characters, things I wish for don't turn gray. Say wha? I'm positive I've wished for the first and fifth items on the first menu of the first selection for Goku, but they're the same color. How do I keep track of the things I've wished for? That item I had wished for was white (instead of green), but it was still there and you could wish for it again.
Is there a reason for this? Can you and should you wish for the same thing multiple times?
You can wish the same items as much as you like, and that is because they will only be useful for you to customize your character.
The thing is, the items you wish for will replace the older ones you had already (the system ones).
System items are the ones that help you during the battle like the stamina, the senzu, etc...