Note: You can find the tutorial here.
For anyone that doesn't know, the Masuda Method is a method that makes it 6 times as likely for an egg to hatch shiny. That is, if the two parents come from different languages. In this tutorial, I'll show you how to add a method that gives eggs a 1/2048 (So 4x more likely) chance of hatching shiny if both parent's "obtain" text is the same.
So. First of all, let's open up to this script, PokemonDayCare. This script has pretty much, if not all, of the egg-related scripts. Now, the method we want is pbDayCareGenerateEgg. This is called when the game decided to generate an egg (It's on line 170).
The next thing you want to do is go down a bit until you see this: # Masuda method
This means that the next trickle of code is the Masuda method. This is it:
if getConst(PBItems,:SHINYCHARM) && $PokemonBag.pbQuantity(PBItems::SHINYCHARM)>0
egg.makeShiny if rand(1024)==0
for i in 0...5 # 6 times as likely
Doesn't make sense? Well, first off, it gets the father's language and the mother's language. if they are NOT equal, continue. Then, it tries to see if you have a shiny charm in your bag. If you do, it makes the egg not shiny, then makes it shiny IF the game randomly generates a number between 0 and 1024 and gets a 0. Now, if you didn't have a shiny charm, then the game tries to redetermine the Pokemon's personalID 5 times, each time checking if the Pokemon is shiny.
Well, that was a lot of explanation. Now, onto what we're adding!
Just below that, add this:
egg.makeShiny if rand(2048)==0
What does that do? First, it compares the father's obtain text to the mother's. If they are the same (ie, caught same place, both daycare Pokemon) the game makes the egg not shiny. Then, the game generates a number between 0 and 2048 and checks if it is 0. If it is, then the egg is shiny.
Well, there you have it! Your own <Insert Name Here> method!
1. Make more methods - Maybe based off natures, IV's, EV's or even the names!
2. Make a second daycare that makes it easier to hatch shiny Pokemon