The item codes don't work correctly for me. All items show up as N/A and it nukes my Z-Ring/Z-Crystal that I got earlier. Maybe the all item code fills with N/A and that's normal? But the UB Balls code does the same. I tried just that one and ended with a ton of N/A items even though I only wanted the UB balls...
So far, using the Item code for Item 1 and Item 2 takes over the ball slot, which isn't a bad thing.
If you let your pokemon hold it, then use a different item code, you'll eventually artificially create more slots to shift around.
Also the description is N/A cause the original item description was wiped away from the data of the demo itself.
They were named N/A with description N/A to maintain the placeholder, to prevent the game from breaking,
in case people like us hacked it in.
However, the item hacking is a bit wonky.
Trying to hack in Friend ball (I wanted to test) using hexadecimal address gave me thick club instead..