Gen6: need a vulnerable web browser app installed (low 3DS system firmware)
Gen7: need a special layeredfs patch installed to the exefs
other: none, just used as a way to share data outside the game.
Lol, wtf it worked. I can't believe the solution was as simple as that. I swear I never got any legal PID before by rerolling so I never really thought of doing that.
Anyway, thanks a bunch.
If I'm not mistaken, based on PKHeX checks for eggs, PID/IV should not have correlation. Reroll the PID, change the location and met level to match having the egg hatched, and try again.