Okay what you just told me made almost no sense. Are you telling me to open the model in brawlbox and click on the sphereN bone and then look on the right side panel for a visibility thing? Because there isn't anything there for that. There isn't anything for that even if I open the animations file on the right. There's no visibility thing in the mdl0 folders. The only part I can find it is in the Vis folder in the FitSonicMotionEtc and that doesn't help me get it to use the ball I put in. It just has these brown boxes inside animations with different bones listed and I don't even see SphereM or SphereN bone specified in them. So if you could explain it again in better detail for me that would be good.
It is on the polygon thing. Not in the previewer but in brawlbox. You just change it to SphereN. If that doesn't work then change it to SphereM. It should be set to TopN by default. The category is called Visibility Bone and there should be an arrow with a drop down list. I hope this helps.