Actually, on Tenkaichi 3, you can get a dragonball on any stage in the story mode. They are hidden inside destructable objects in the environment. Some stages, like the City stage (sorry, can't remember if it's south, west, or central city) will be hard to find a dragonball because they can be hidden in the buildings, the trees (very rare), the cars, etc. Desert stages, they are usually hidden in the big rock formations. All you have to do is fly around away from the opponent, get directly behind the rock formation, and use either several Ki blasts or a super move. Sometimes it takes a while to find it, while other times its relatively easy. There have been times where I didn't find one at all, but then again, there's always that little thing that you can miss. Hope I helped!
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