Is it just chance that two Pokemon will like each other while breeding, even if they're in the same egg group?

Question

Because when I breed Pokemon with Ditto, sometimes the guy says they like each other, or they don't, and if they don't, they take longer to breed, or don't breed at all? I just don't really understand.

Answer 1

I mean chance after 255 steps When I say chance

Same species, different ID numbers

The chance of getting an Egg is
69.3% (has a value of 70). The Day-Care Man will say: "The two seem to get along very well." This chance is raised to 87.8% when wielding an
Oval Charm (has a value of 88).

Same species, same ID numbers

The
chance of getting an Egg is 49.5% (has a value of 50). The Day-Care
Man will say: "The two seem to get along." This chance is raised to
79.5% when wielding an Oval Charm (has a value of 80).

Different species, different ID numbers

The chance of getting an Egg is 49.5%
(has a value of 50). The Day-Care Man will say: "The two seem to get
along." This chance is raised to 79.5% when wielding an Oval Charm
(has a value of 80).

Different species, same ID numbers

The chance of
getting an Egg is 19.8% (has a value of 20). The Day-Care Man will
say: "The two don't seem to like each other." This chance is raised to
39.3% when wielding an Oval Charm (has a value of 40).

Different Egg Groups, same genders or Undiscovered group

The Pokémon are
incompatible and therefore will not make an Egg. The Day-Care Man will
say: "The two prefer to play with other Pokémon than each other."

Comments

Both of you helped. The last thing you say the day care man says sounds like its reffering to something else... The stuff you don't see that goes on in the daycare...

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If I get a Ditto from someone else it will help with breeding then thanks!

Answer 2

Two Pokemon not of the same egg group will ignore each other.
Two Pokemon of the same egg group, same species, or a Pokemon and a Ditto that all have the same trainer ID will not like each other very much.
A Pokemon and a Ditto or two Pokemon of the same egg group with different trainer ID's will get along okay.
Two Pokemon of the same species (I.E. Eevee) with different trainer ID's will get along fantastically.

Basically, it goes egg group, trainer ID, species.

Source : http://www.gamefaqs.com/boards/696959-pokemon-x/67732817

Hope I helped!