Unable to match an encounter from origin game Pokemon X/Y & AS/OR

[LeifValz]

Guys, need some help with this:

I tried to edit my gift Pokemon like Lucario or Latias, especially their nature.
Once I done that, there's always a notification about "Unable to match an encounter from origin game."
I honestly don't know what to do. Can anyone help me regarding this matter?

Thank you

[BlackShark]

That depends on what exactly you are trying to change. For Lucario the ability, IVs and nature are fixed and can not be changed.