I forgot that decor items were missing in PKHeX and so I found their offsets that I jotted down on notepad recently!
Note that this was tested on ORAS and may differ from XY. I'll let other testers find out about XY since I don't have much time on my hands.
16E00-170AC (I highlighted 16E00-170AD right-clicked -> Fill Selection.. -> Set Hex Values as "01 00" and so it gave me 1 of each, dunno the max quantity of each decor; 999 gave a "?9" in-game so i don't think that's the max per item)From Cocoa Treat Cusion through Wooden Bed as listed on bulbapedia[/Code][Code]All Wall PaperSetting the bytes located @ offsets 170B0-B3 to FF should give all 34 of these.
Bonus: For O-Powers, to have all non-S levels (since PKHeX's includes all S) in my save file the bytes appear as they do from offsets 17401-17447
01 01 01 00 00 01 01 01 00 00 01 01 01 00 00 01 01 01 00 00 01 01 01 00 00 01 01 01 01 01 01 01 01 01 01 01 01 00 01 01 01 00 00 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 0A 00 00 02 00 0B 04[/Code]
Hope I helped and I know everyone's busy with SM on the horizon as of writing, but it's better late than never.