Rocky Helmet in general is almost exclusively used on defensive Pokemon, and most of them have Status or Knock Off, so you will never be switching into them. Pads are a waste of item slot on Shedinja.
Edit:
INSANE CARZY GUY Shedinja is not used to do substantial damage tbh. I could consider adding the move to OO, but it will never be preferred over Shadow Sneak, or even slashed onto the main set. Priority, winning vs Ditto, etc. is far more important