During my playthrough of Pokemon X this past week, I found 2 shinies (Quagsire and Absol) in the wild. After I completed the game, I felt the thirst to acquire more and more shinies. I tried the masuda method, got the foreign ditto and everything, however I was instantly bored with it. My grievance with MMing for shinies is that there is no assurance of when you will get your shiny, if you ever actually do; it could be 3 eggs or 3000 eggs. I knew about chaining from previous gens, but never tried it out of fear for its complexity. Chaining can be frustrating, however it is very rewarding, as if you do it correctly, you are guaranteed a shiny.
What is chaining?
Chaining, in simple terms, is the act of encountering a pokemon over and over again using an item called the PokeRadar. For those of you that don't know, you get the PokeRadar after the Elite Four in Professor Sycamore's Lab in Lumiose City on the 2nd floor. The PokeRadar works like this: you use it in some grass and patches of grass around you shake, indicating a pokemon is in one of those patches. The PokeRadar recharges after you take 50 steps.
Why should I chain?
Chaining on its own is very boring, and seemingly unimportant. However, if you are able to chain a pokemon 40 times successfully, certain "shiny patches" will start to show up every few resets of the PokeRadar. These patches indicate a shiny pokemon dwelling in this grass, aka when you enter the grass, you get shiny.
What are the rules/steps to chaining?
While there are no concrete laws to chaining and everyone has their own methods, I will explain the method I have found works 100% of the time for me. It took me a disgusting amount of testing to figure these principles out.
Buy super repels. A lot of them. These will ensure that you do not break a chain of encounters by running into wild pokemon in the middle of chaining. Also, I should emphasize the phrase a lot of them. I usually bring around 200. Nothing is worse than running out of repels at a chain of 20. (I should mention max repels work fine as well, however it is more cost effective to use super repels as max repels only give 50 more steps for $200 more.)
Put a pokemon with moves that have a lot of PP in your party. I would highly suggest a pokemon with 2 moves with 20pp or 1 move with 40pp, as it makes counting much easier.
EDIT: /u/bgw92 says to register the poke radar and unregister any other items, as using another key item breaks the chain.
Find a field of grass with at least 5 patches of grass by 5 patches. It is important to have a large field and this will be explained shortly.
Walk into roughly the middle of the field and use your PokeRadar, making sure you've already used a super repel. Several patches of grass will shake.
Walk into one of the patches of grass, being sure to remember the nature of the shaking. There are two types of shaking, I will refer to them as rough and soft shaking. Rough shaking is, well, rough shaking and soft shaking is the opposite.
If the pokemon you encounter is one that you would like to chain, KO it. This will ensure that the chain continues off of that pokemon. Congrats, you now have a chain of 1. (You can use a notepad to count your chains, but I find it's easier to count with your pokemon's PP.)
After you KO the pokemon, more grass will shake. PAY VERY CLOSE ATTENTION TO THE SHAKING GRASS. This is easily the hardest part of chaining as well as the most confusing. Not every grass will yield the pokemon you previously KO'ed. There are a few rules to making sure the pokemon is the same. 1: The grass must be of the same nature of shaking, ie: if your first grass was a rough shaker, only go to rough patches. 2: Only go to a patch that is at least 4 spaces horizontal or vertical away from you. There is much disagreement among this rule and you may find that another distance works better for you. However, if you're just starting, I would recommend doing everything in a very formulaic fashion. 3: If no patches meet this criteria, simply reset the PokeRadar until a patch works. Do this by running back and forth inside the field of grass, taking care to not run over one of the patches that wouldn't work. 4: If you KO a pokemon in a patch that is on the edge of the field (ie if the grass is not surrounded on all sides by other grass) you must reset your PokeRadar. Many chainers believe that KO'ing a pokemon on the edge of a field is a death sentence for your chain. This is only true if you do not reset after you KO an edge piece. If you neglect to reset, there is a good chance a shaking grass (even if it fits aforementioned criteria) will give a message saying "It seems there is no pokemon here," which will break your chain in a very demeaning manner. 5: When you finally reach a chain of 40, pat yourself on the back and take a bathroom break (it's been stored up for awhile now I'm sure). When you come back, it is unnecessary to chain any more pokemon. Getting a chain of 40 or 70 yields the exact same odds of getting a shiny. What you should do is reset your PokeRadar over and over again until you see a patch that shines. I would suggest having the volume turned on at this point because when shiny patches appear they emit a pleasant sound. You shouldn't be able to miss the shiny patch, as it is made very clear which patch is shiny. 6: Catch the shiny and bask in its shiny glory.
Ways in which a chain can break
Entering a patch of grass that does not have the pokemon you have been chaining.
Entering a patch of grass and having the message "It seems there is no pokemon here".
Leaving the field you are chaining in.
Turning off your game.
Using the roller skates.
EDIT: /u/thekingofnarwhals said he hatched an egg while chaining and it broke his chain.
EDIT: /u/Minkelol said his chain broke by encountering a wild pokemon even when he did everything right. This could confirm a very small chance that another pokemon can show up even if you do it right.
Some rare occurrences and how to deal with them
Sometimes if you enter a patch of grass on accident that does not fit the criteria, you may still encounter the pokemon you were chaining. In this case, you are very lucky. However, next time you may not be so lucky.
"Hey, I accidentally entered a patch of grass that had a different shaking than the one I've been using and I still found the same pokemon!" If you happen to notice when this happens (which you likely won't) you have two choices. Essentially, what has just happened is you have "reset" the type of grass your chain is associated with. This means you could continue the chain with the new grass shaking and everything is fine. However, if you're like me and cannot notice one patch as well as the other, I would suggest just resetting your chain, if it's still a pretty small chain.
After the Elite Four, you may have noticed a certain legendary bird occasionally occurring in wild grass. These guys are unaffected by repels, so many have come to believe that encountering a bird messes up your chain. THIS IS NOT TRUE, PRAISE GOOMY. The legendary bird runs away and has no effect on your chain. Zip. Nada. Zilch.
"Help! The pokemon I've been using to KO the others is out of PP!" Calm down. Using the menus for anything does not break your chain, even if you save. However, saving in the middle of a chain does nothing because when you reset your game a chain is broken.
"My power died!" Sorry, chain broken. Next time pay attention to the lovely notification on the bottom screen when your battery is low.
Well, I think that about covers it! If anyone has any additions, let me know and I shall add the information into the tutorial, giving you credit.
EDIT: Wasn't sure where to put this one, but /u/mansharkcow claims there are actually 3 types of shaking (soft, medium, large) and that serebii says that the more a grass shakes, the rarer the pokemon inside is.
EDIT: /u/HallucinatesTigers found this and this (two videos showing the shiny patch animation/sound)
EDIT: /u/Mouseshy has potentially found an interesting correlation between IVs and Chaining.
EDIT: Going to bed now, will hopefully answer all of the questions that arise when I wake up! Goodnight reddit
EDIT: Hello all, I've noticed a lot of positive reception from this post and I was wondering if you guys would find another tutorial post like this useful. Let me know!