X/Y Egg RNG Trick Guide

RNG Trick in X/Y

Pre-requisites

• Destiny Knot
• Everstone (optional)
• Hatching O-Power (optional)
• Access to Kiloude City, post-game (optional, but the IV Judge is in the Pokemon Center)
• Decent sized pool of multiple Ditto/Pokemon with good IVs (Friend Safari guarantees at least 2 perfect stats)
• Scouting Parents: Gather two breedable Pokemon with different IVs from each other. Know both their exact IVs or at least narrowed IV ranges.
  
  Male 31 / 31 / 31 / 31 / 31 / 31
  
  Female 8-9 / 21 / 4 / 17 / 23 / 14

The Process

1. Put your two Scouting Parents into the Day Care. I like to use two Gyarados to scout the egg inheritance of the next 1 frame because Magikarp hatches very quickly. In this example, I'm using a male Gyarados with six perfect IVs and a female Gyarados with crappy random IVs like above. One must hold the Destiny Knot, and if you prefer ideal natures, make the other parent hold the Everstone then.
2. Bike around until the Day Care Man is facing the road and has an egg. Reject the egg. Save.
3. Continue bicycling around until he has another egg. Collect it, hatch it, and note its nature and characteristic.
4. Find out the baby's IVs. Take it to to the IV Judge in Kiloude to pinpoint any perfect 31 IVs. Then, go to the Battle Institute to check its exact IVs (take a cab to it in Northern Lumiose City).
5. Start figuring out the baby's egg inheritance. In my example, the newborn Magikarp has the following IVs:
   
   8 / 13 / 4 / 31 / 31 / 31 This means the baby inherited the flawless Spatk, Spdef, and Speed from the male. The baby inherited terrible HP and Defense from the female. The IV not inherited was 13 in Attack, considered the wildcard. I'll illustrate the inheritance using a red F if the female passed the IV down and a blue M if the male passed the IV down. The wildcard IV is *.
   
   F / * / F / M / M / M
6. Soft Reset the game using L+R+Start. Reload your save from the point where you had just rejected the egg.
7. If you like the spread, go into the Day Care building and look in your PC storage for a couple matching the inheritance. In this example, the inheritance is good for a special sweeper since Attack isn't important. I need a female with perfect stats in HP and Defense and then I withdraw my desired female. My perfect Gyarados is fine for me to keep on using.
8. Place the new couple of your desired species with Everstone & Destiny Knot equipped in the Day Care. Bike around for an egg. Collect it, hatch it, and take it to the IV Judge. It should have inherited the same IVs that you earlier found.
9. If you do not like the spread and/or do not have anything that can make use of the spread: Reject the egg. Save. Bike around for the next egg and start at Step 3 above.

Nov 14 edit: Genders didn't seem to change inheritance spread, but the baby may switch genders if you're using different gender ratios than from the scouting parents. You don't have to use a father with 6 perfects; it was an example. Both parents should have different numbers from each other as otherwise, if both have have 9 in Attack, you can't tell which one passed the stat down to the baby, now would you? You don't have to reject the egg in the beginning. I stopped doing that and this trick still worked. The inheritance was set the moment I collected the previous egg, apparently. Dec 13 edit: Everstone is not required, but it is used to pass one parent's nature down 100% of the time.