I don't think any real tools have been made for this yet (which would explain the lack of quality in most of these, especially visual), but I'm betting they will be at some point if this has gotten this far. I really need more good Super Monkey Ball seeing I finally beat Master a while back...
I also found that around the same time custom levels were being introduced, a glitch allowing you to skip different sets of levels (Expert vs Expert Extra vs Master) has been figured out (15+ years later!): If you break the tape on the goal post once the timer reaches 00:00, you'll loose a life, but if you break it again, you'll warp to the next set of levels: https://www.youtube.com/watch?v=w77MWUsQQ_k
You know, if this has been done, I think we're one step closer to custom F-Zero GX courses! (Seeing that Nintendo isn't making another F-Zero anytime