idiggory, King of Bards wrote:
The quick and dirty of it is that the mother determines the pokemon species, and the father can contribute moves (which is how you can breed a pokemon with moves it wouldn't otherwise learn).
All pokemon belong to one or more egg group, and they can breed with any pokemon in this egg group.
The exception is the pokemon that belong to the undiscovered egg group (like most legendaries). They can't breed at all.
Ditto can breed with any non-iundiscovered pokemon, but you can't breed ditto and ditto.
When you breed with ditto, it's always the species of the other pokemon.
To get pokemon to breed, you leave them at the day care. Based on their compatibility, there's a set chance of them producing an egg every 250 steps you take (every "node" you move).
Ok cool. So lets assume:
I have a dude Beedrill who knows Bug Bite, and a Female Butterfree.
I leave them at the bang shack and might get an Egg that should be a Caterpie who might know Bug Bite.
Alternatively I have a dude Charizard with Dragon Rage, and a Ditto
I leave them at the bang shack and might get an Egg that should be a Charmander who might know Dragon Rage.
(also how do I locate Egg Groups is it in the Pokedex?)