OK so with no proven answer I've had to grind through 'aS' and 'Y' to try this out on Seviper. From my experience it seems that wild hold items on X/Y are not available on oRaS (I never found the Persim Berry in 'aS'). There are 3 exceptions, Solrock, Lunatone, and Clamperl, but according to Bulbapedia, the X/Y item in each of these cases aren't exclusive and are listed for all four games, with these Pokémon having added items available in oRaS. Also, in many cases those with an oRaS exclusive item never had an item for X/Y in the first place. It would seem that for wild Pokémon hold items Bulbapedia is more reliable. This is only based on my experience, but until some one can prove otherwise, this will have to suffice as an answer