I was wondering why the spotpass add-ons are banned? Is it due to them being busted or due to the fact they're spotpass add-ons?

Its due to them being spotpass. Typically its disallowed to use things like spotpass and street pass in speedrunning.

Thanks for the reply, I was also wondering if spotpass could be implemented into a subcategory or do you believe there would be a lack of interest in that?

The game has whopping one run from more than 3 years ago, I think any activity whatsoever for the game would be good. If you're interested in running the game just run it the way you want and the rest can be figured out after that.

True, thanks for the response.