Why is Trainer ID and Secret ID necessary in order to get a PID for a Shiny?

[SteveBob]

PIDs aren't random as far as I can tell so why would the trainer have an effect on them? If a PID can't be found for one trainer it wouldn't be possible for any trainer right? So why is it necessary in PID generators?

[XboxOmac]

PID Generators so you can have legit pokemon. Not legit pokemon pretty much isn't allowed like in Wi-Fi and all that.

[SteveBob]

I know but why does it need you trainer/secret ID in order to generate them? It only seems to be necessary for some generators but I haven't seen one that can generate shinies without them. Basically, what I want to check is... Is it possible to get/not get certain PIDs depending on your trainer/secret ID or do they remain the same in every game no matter what ID you use?

[Tundra_Blitz]

Well, the game is widely based on your trainer ID and secret ID. It uses a ridiculously huge (or I should say tedious) formula to generate the likely hood of getting certain shiny pokemon, and what their IVs are. So without those two little pieces, then a legit shiny can't be made.

[SteveBob]

Hmmm that makes sense. Still, changing my ID's won't allow me to get a certain Pokemon I couldn't get with the previous ID will it?

[Tundra_Blitz]

No... Basically, you have millions of possibilities already with your ID/SID, it's just in what order they come in. Changing your ID/SID won't really change the number of outcomes, but it will change the order in which you may (or may not) receive them.

[SteveBob]

Cool, thanks