Sun and Moon have significantly changed the breeding mechanic. In ORAS, I could save before picking up eggs, hatch them, then soft reset (SR) back to the save, and get a completely new set of eggs (i.e. the egg was determined at the point you collected it from the daycare - more specifically, it's determined at the point you collect the egg before that one).

However, in Sun and Moon, egg statistics (stats/IVs/gender etc) are determined at some point before you pick up the egg from the Daycare. I've saved, collected and hatched 5 Pokémon, SR'd, then collected and hatched the exact same Pokémon, down to their IVs.

I much prefer this method as it means you don't fill up countless boxes with the same inadequate Pokémon in the quest to find one with perfect IVs and Nature (same applies for Masuda Method if shinies are your thing).

See title for the resultant question.

  • Probably statistics are now determined when the egg is generated at the daycare.
    – pinckerman
    Dec 8, 2016 at 15:52
  • If this post is correct, it looks like it's predetermined even earlier... but that seems wrong.
    – Vemonus
    Dec 8, 2016 at 15:54
  • This means that there's a sort of fixed seed for the RNG that determines each offspring's statistic, which is not dependant on the clock (because parents' withdrawal and deposit don't affect it). Kind of.
    – pinckerman
    Dec 8, 2016 at 16:02

2 Answers 2


Eggs are generated when you pick them up. As soon as you choose to receive an Egg, the game calls the Egg RNG (Random Number Generator) to determine the Pokemon's characteristics.

The big difference to previous generations is that this Egg RNG is completely independent and never reseeded. It's exclusively used for eggs and once the starting seed is determined (presumably when the game is first started), it carries over forever and is saved with the game. This leads to soft resets not having any effect and allows for exact predictions assuming the current seed can be determined.

One notable detail is that the PID (which determines shininess and not really anything else nowadays) is generated by yet another RNG, potentially the game's main RNG, and is thus unpredictable for practical purposes. However, when shiny charm or the Masuda method are used, this initial PID is discarded and additional PIDs are generated by the Egg RNG, making shininess predictable again if either or both of these methods is used.

The Japanese community have put a great deal of effort into this and discovered nearly the entire mechanics behind this by the time the English-speaking community independently discovered there was something fishy. There is actually an English guide made by one of the Japanese researchers that details how to determine the current seed and use a tool created for this specific purpose to predict eggs and even search for specific characteristics.

My sources are various, most of them are google-translated Japanese sites and personal experiences. The guide linked above sums up the relevant information for anyone who's not too interested in the actual programming stuff going on.

  • So... when using Masuda method, the number of eggs before a shiny is fixed? So you could save, breed a bunch of Magikarp, check which one is shiny, then reset and breed the Pokémon you want to be shiny? Feb 16, 2017 at 21:01
  • @DanmakuGrazer That's correct. There are a couple things to look out for, though. For the best efficiency, collect one egg less than it took to get a shiny Magikarp, then switch the parents. If they are genderless or have a fixed gender, reject the next egg, then collect your shiny. Make sure the same items are in use, specifically Destiny Knot and Power Items (only the number matters, it's irrelevant which parent holds which item and you can even change which Power item is being used as long as you still use either two, one or none).
    – scenia
    Feb 16, 2017 at 21:08
  • @DanmakuGrazer I'll point out there is a significant chance of skipping a shiny with this method. If a random number that would produce a shiny PID is used for, say, the Attack IV, you've essentially skipped a chance to get a shiny. Rejecting eggs uses up one frame, so it's possible to slightly adjust the frames you're landing on as long as you know where you are. This is actually the basis of the abuse method since reseeding is impossible, you can only pick the right frames.
    – scenia
    Feb 16, 2017 at 21:11

According to a post I saw on reddit, certain characteristics of the Pokemon are determined in a pattern that is fixed before the Pokemon are even placed in the day care.

This was proven by hatching eggs without saving until a Shiny Pokemon was obtained, noting which number egg hatched to give the shiny, then soft resetting, putting different Pokemon into the Nursery, then hatching the eggs again. The exact same egg 'number' was also a shiny Pokemon despite being a different species. This pattern was repeated no matter the Pokemon placed into the Nursery.

At the very least, this proves the 'Shiny Value' of the egg is set on a pattern regardless of what the egg actually is. What determines this generation is still to be determined.

  • 4
    Could you link the Reddit post you reference?
    – Angzuril
    Dec 16, 2016 at 23:09

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