Hi,
I made a tool that takes your save1keystream.bin and a matching Powersaves .bin from the same game, then generates a completely decrypted save file that you can open up and edit freely in PKHeX.
You can download the binary release here. If it says something about a missing DLL, please tell me what it is, preferrably in PM!
If the binary release doesn't work for you, download the source code here. You'll need to install Qt5 for it to compile and run.
Enjoy!
Update 2015-01-04: ORAS suppor