Breeding is a method of obtaining a new Pokémon by producing and hatching an Egg.

How to breed

Pokémon can be bred by leaving two compatible Pokémon at the Pokémon Day Care located on Route 9. Two Pokémon are compatible if they are of the same egg group and are of opposite genders. Alternatively, Duplicat can be used as a substitute parent, as they are able to breed with all Pokémon from breedable egg groups, and genderless Pokémon can be bred only with Duplicat. Pokémon in the Undiscovered egg group and Duplicat egg group cannot breed, thus, Duplicat cannot breed with itself.

For a full list of Pokémon's egg groups, as well as other information such as hatch time and gender ratio, please see List of Pokémon by breeding stats.

Breeding rate

The chance of any two Pokémon producing an Egg is determined by their species (two Raptorch are the same species, while Raptorch and Archilles are not), their Original Trainers(OT) and oval charm. The Day-Care Man will describe the two Pokémon's compatibility when the player speaks to him. An Egg may be generated after every 256 steps the player takes.

Species Original Trainer Quote Chance for Egg (with Oval Charm)
Same Different "The two seem to get along very well" 70% (88%)
Same Same "The two seem to get along." 50% (80%)
Different Different "The two seem to get along." 50% (80%)
Different Same "The two don't really seem to like each other" 20% (40%)
Different Egg Group, Same gender or Undiscovered (Egg Group) Same or Different "The two prefer to play with other Pokémon more than with each other." 0% (0%)

Inheriting stats

If at least one parent holds a Destiny Knot, the offspring will inherit 5 IVs at random. This can be combined with a EV-boosting item to ensure that one desired IV is always inherited as opposed to those of a random stat. However, the offspring will still inherit only a max of five IVs from its parents (the EV-enhancing item simply guarantees which IV will be transferred for one of the five that the Destiny Knot allows).

Without the Destiny Knot, only 3 IVs will be passed and the other 3 will be random.

Inheriting Natures

If one parent holds an Everstone, its Nature will always be passed down. If both parents are holding an Everstone, a parent's Nature will still always be passed down, but which parent's Nature is passed down is randomly determined.

Inheriting Abilities

It is possible for a Pokémon's Ability(including Hidden Ability) to be passed down to the offspring. Female Pokémon have an 60% chance (the other 40% will be random), whereas the males have a 20% chance when bred with a Duplicat. The ability of the father is always irrelevant when bred with a female.

For Pokémon such as Pufluff that have only one ability in their pre-evolved form and multiple abilities in their evolved form, the ability of their evolved form will be random, but it will be determined when the player gets the egg, so soft resting to evolve the same Pokémon again will not yield an evolved form with another ability.

Hatching Eggs

Eggs will hatch after the player travels a specific amount of steps with the egg in their party. The number of steps needed vary depending on the species of Pokémon and can be found on the page for each Pokémon.

Having a pokemon with the Flame Body ability or the Magma Armor ability in the party will allow each step to be counted as 2 steps, thereby halving the amount of steps needed to hatch the egg. However, this does not stack with multiple bearers of one ability nor having both abilities in the party.

Egg Moves

Moves that are registered as egg moves of a certain Pokémon will be passed down if either its mother or father has the move. They are relearnable from the Move Reminder in Venesi City if the Pokémon was born with the move and somehow forgot the move.

Moves that the Pokémon can learn by leveling up can be passed down to the offspring if both parents have the move when producing the egg. They will not be passed down if only one parent has it. They are not relearnable via Move Reminder after being lost.

TMs that the Pokémon can learn are passed down if the father have them.

Shiny Pokemon

The chances of breeding a shiny Pokémon in Pokémon Uranium are only affected by 2 factors- using Masuda breeding and having the Shiny Charm.

Masuda breeding refers to breeding 2 Pokémon that are from different countries. In Pokémon Uranium, the country where a Pokémon is from can be found in the summary page of the Pokémon in the form of a tiny flag. If the Pokémon is from the player's country, there will be no flag.

The chances of breeding shiny Pokémon in Pokémon uranium are as follows:
normal rate = 1/1024
with shiny charm = 3/1024
with masuda = 6/1024
with both = 8/1024
(rates provided by Kiryuu)

To clear some misconceptions, breeding shiny Pokémon will not affect the rate of shininess in offspring.