Breeding two Pokémon at a Nursery or Day Care doesn't produce a random egg — every stat, Nature, and learnable Egg Move on the offspring is the output of specific inheritance rules the player can manipulate directly, which is why competitive breeders can reliably produce a specific target spread (Nature, five near-flawless IVs, a chosen Egg Move) rather than hatching hundreds of eggs and hoping.
IV Inheritance and the Destiny Knot
Without any held items, an egg inherits a small random handful of IVs directly from its two parents, with the rest rolled fresh. Destiny Knot changes that ratio dramatically: when held by either parent, it causes the offspring to inherit five of the twelve total individual IVs (six stats across two parents) directly from the parents, chosen at random from which stat and which parent each of the five slots pulls from. That's the core mechanic breeding chains are built around — pairing two parents that are each flawless (31 IVs) in different stats means most inheritance draws land on an already-perfect IV, and only the uninherited stat slots need to be improved through further breeding generations.
Everstone and Guaranteed Nature
Nature inheritance works on a separate, simpler rule: if either parent holds an Everstone, the offspring's Nature is guaranteed to match that specific parent's Nature 100% of the time, overriding the random Nature roll entirely. This is why competitive breeding projects almost always keep one parent locked to an Everstone holding a specific Nature for the entire chain — it removes an entire axis of randomness, leaving only the IV rolls (mitigated by Destiny Knot) as the remaining variable to grind out.
Everstone Interactions With IV Inheritance
Everstone and Destiny Knot can be held simultaneously by the two different parents in a single breeding pair, and because the two items govern completely separate inheritance rolls — Nature from whichever parent holds Everstone, IVs from the Destiny Knot-driven five-slot pull across both parents — running one of each at the same time is standard practice rather than a conflict. The one interaction worth flagging explicitly: Everstone's guaranteed-Nature effect does not consume one of the five Destiny Knot IV inheritance slots, and it doesn't interact with which parent an individual IV slot happens to pull from either. The two mechanics run independently in the same egg-generation step, which is exactly why a breeding project can lock Nature on one parent and stack Destiny Knot IVs from both parents in the same single pairing rather than needing separate generations for each half of the job.
Egg Groups and Egg Moves
Two Pokémon can only breed together if they share at least one Egg Group (a hidden compatibility category assigned to every species), or if one of the pair is Ditto, which is compatible with nearly every breedable species regardless of its own Egg Group, with one specific carve-out: Ditto cannot breed with any Pokémon in the Undiscovered Egg Group, a category reserved for Pokémon the games don't consider breedable at all — most Legendaries, Mythicals, and several evolution-line-final baby-less species fall into Undiscovered specifically to block them from the Nursery entirely, Ditto included. Egg Moves are the mechanic that makes Egg Groups matter beyond simple compatibility: a move that a target species cannot normally learn by leveling or TM can sometimes be passed down if the father (or, in some game generations, either parent depending on which one already knows the move) knows that move at the time of breeding and shares an Egg Group with the mother. This lets breeders assemble movesets a Pokémon could never legitimately access through its own level-up or TM list otherwise, and it's the standard route for building genuinely optimized competitive movesets rather than settling for whatever a wild-caught individual happens to know.
Hidden Ability Inheritance
A Pokémon's Hidden Ability — the rarer third or fourth ability slot, historically only obtainable through specific event methods before becoming more accessible in later generations — has its own separate inheritance rule distinct from both Nature and IVs. When the mother (or a female-capable parent) holds a Hidden Ability, the offspring has a high chance, though historically not a guaranteed one, of inheriting that same Hidden Ability rather than defaulting to one of the species' regular ability slots; that chance is typically cited around 60% in the generations where the exact rate has been datamined, though some titles have adjusted it closer to a near-guarantee. Ditto complicates this rule in an important way: because Ditto has no gender and functions as a universal parent regardless of which slot it's paired into, a Hidden Ability Ditto paired with a genderless or male-only target species is often the only practical route to passing a Hidden Ability down at all, since the normal 'female parent passes it' rule has no female parent to apply to in those pairings.
Chaining It Together: A Practical Breeding Project
A full competitive breeding project usually runs in this order: first, secure a parent with the desired Nature and hold an Everstone on it for the rest of the project; second, secure two flawless-or-near-flawless parents whose strong IVs cover all six stats between them and pair them with Destiny Knot to consolidate those IVs onto offspring; third, once IVs and Nature are locked in on a stable breeding pair, swap in a father that knows the target Egg Move for one final generation to pass the move onto an offspring that already carries the correct Nature and IV spread. Skipping the order — trying to lock Egg Moves before IVs are settled, for instance — usually means re-breeding the Egg Move back in repeatedly every time a new IV-improving pairing is tried, since inheritance rules apply fresh to every single egg rather than accumulating.
Shiny Odds: The Base Rate
In modern mainline games, the base shiny encounter rate is 1 in 4096 for any individual encounter, egg hatch, or generation event, replacing the much steeper legacy odds from earlier generations. That 1/4096 figure applies with no special conditions met at all — every single Pokémon a player encounters is quietly rolled against that rate before anything else is considered.
The Masuda Method
Breeding two parents whose game cartridges were originally saved in different language settings (an English-language game bred with a Japanese-language game, for example) improves the odds of a shiny hatch from the base pool, roughly to about 1 in 683 — the exact improvement comes from the game adding extra shiny-check rolls specifically to eggs bred this way rather than changing the base rate directly, but the practical effect is the same: a substantially better shiny rate on hatched eggs versus wild encounters, provided the two breeding parents are confirmed to be from differently-localized game copies.
Stacking the Shiny Charm
The Shiny Charm is a key item (typically awarded for completing the regional Pokédex) that adds its own extra shiny-check rolls to every encounter type, including eggs. Used on its own it meaningfully improves the base 1/4096 rate; combined with the Masuda Method on a breeding project, the two extra-roll bonuses stack, pushing hatched-egg shiny odds to roughly 1 in 512 — the best realistic shiny rate available through legitimate hatching, and the reason serious shiny hunters treat completing the Pokédex (to unlock the Shiny Charm) as a prerequisite step before starting a big breeding project rather than an optional bonus.
Chain and Odds-Boosting Methods Beyond Masuda
The Masuda Method and Shiny Charm both work by adding extra roll attempts to a single encounter type — breeding — but several generations have shipped entirely separate systems that boost shiny odds through repetition rather than parentage. SOS chaining, introduced in Sun and Moon, let a wild Pokémon call for help repeatedly through a specific held-item-and-move interaction, and each successive ally that joins the chain without the chain breaking increases the cumulative shiny check for that encounter, meaning a long, carefully maintained SOS chain of several dozen calls could push shiny odds dramatically higher than a single unmodified wild encounter — at the cost of the chain resetting to zero the instant the original Pokémon faints, flees, or is caught before the player is ready to end the hunt. Dynamax Adventures, introduced in the Crown Tundra expansion, works completely differently: every legendary encountered inside a Path of Legends-style four-player raid den has its shininess rolled fresh on that specific raid attempt, and because Dynamax Adventures let players run the same den repeatedly in quick succession without the usual once-per-save legendary restriction, the method turned normally single-encounter legendaries — Pokémon that would otherwise offer exactly one shiny roll per save file — into a repeatable, chainable shiny hunt for the first time in franchise history. Both methods share the same underlying philosophy as Masuda: don't wait on the base 1/4096 rate, manufacture more independent rolls at it instead.
Why Breeding and Shiny Hunting Are the Same Project
Because a competitive IV/Nature/Egg-Move breeding chain and a Masuda Method shiny hunt use the exact same Nursery mechanic — two compatible parents producing a stream of eggs — experienced players run both goals simultaneously by default: pairing differently-localized parents for the Masuda bonus while also holding Destiny Knot and an Everstone for the IV and Nature targets, so that the eventual 'good' egg (right Nature, right IVs, right Egg Move) has already been rolling against improved shiny odds the entire time rather than needing a completely separate hunt afterward. The only real friction between the two goals shows up when a target species is Undiscovered-group and therefore unbreedable at all — in those cases the Masuda Method and Destiny Knot inheritance simply aren't available, and a shiny hunt for that specific Pokémon has to fall back on repeated wild encounters, SOS chaining where applicable, or a Dynamax Adventure run instead of the Nursery-based approach that covers every other target on this list.