Board Thread:Manga Discussion/@comment-36009107-20180805142852/@comment-1739368-20180805164254

I dont think they're necessarily "on" at all times, but users can have them active inside of them when they need to; they show it a couple times during the Jotaro vs Dio fight.

And yeah, I think Users with at least humanoid close-range Stands should be able to fist fight, but there's generally little reason to do so.