Help with Gen 9 genning

[Eggs]

Hi, just wanted to know if there were any rules or caveats to modifying a caught mon in gen 9 and genning one from scratch?

I'm unable to mod my switch so I'm planning to use a sysbot to get pk9 files of my mons ingame, edit them, then trade them over to my game. Will there be any PID mismatch shenanigans if I make my mon shiny or change its IVs?

Also, I tested creating a Walking Wake from scratch using the Encounter Database. It appeared I could change everything about it except for its IVs, (non-stat) nature, height/weight/scale, and encryption constant. Any reason why? I assume it's because there are fixed spreads for Tera Raid mons since the error it was giving me was "unable to match encounter from origin game" and I could 'reroll' the values when I clicked on view from the database to refresh the mon.

Edited March 14 by Eggs