How do you you breed Pokemon on Pokemon Diamond?

Answer 1

there is many ways you can breed like cloning but the way i do it is get a ditto from leaf green or fire red or emerald migrate it to diamond and put it in the day care with the Pokemon evolution of the Pokemon and wait for the egg

note: will not work with legendaries apart from manaphy

Answer 2

put male and female Pokemon in daycare

there is a whole book dedicated on this, but I'm just going to make this short. There are different egg groups for Pokemon. Pokemon can be in more than one egg group. for Pokemon to breed at least one of their egg groups has to be the same. most legendary Pokemon do not have egg groups, but im sure theres already an action replay code for that. ditto has his own special group because he is a Pokemon that allows you to breed some legendaries and do other things you couldn't do with any other Pokemon. like if you put ditto and manaphy in the day care youll get the legendary Pokemon phione. also, some Pokemon don't have a gender. the ones you can breed with you can breed with a male a female or another Pokemon without a gender. ditto does not have a gender.also, theres these cool things you can do by just making one of your Pokemon hold a certain item. like if you give a female pikachu a light ball and breed it with a Pokemon from the fairy egg group, youll get a pichu that knows volt tackle.

Answer 3

get a female and a male of the Pokemon then put them in the day care and come back about a day later and there might be an egg there.