Nope. Like almost all Legendaries, Dialga is genderless and will not breed.
you need to get two Pokemon and breed them in the day care centre
The Day Care Centre is west of Mauville City.
a cranidos egg.
they don't breed.
You breed it at the Day Care.
put it in day care with a ditto
at the day care
The Day Care Centre is on the left side of Solaceon Town.
day care
It is in Mauville City.
You breed them in Solaceon Town (I might have not spelled Solaceon right) in the Day Care. The Day Care is the top left house in the town.
you get a ditto and take it to the day care centre and then get an eevee from the girl next door to the Pokemon centre in hearthome city then put it in the day care centre. if they stay there long enough you get an egg and when it hatches its an eevee Do this as many times as you want cheers get a ditto and go to the day care centre then get a eevee from the girl next door to the poke centre in hearthome. put them both in the day care centre together and after a while an egg will appear . the egg will hatch soon after and it will be an eevee. Repeat this as many times as you want. Cheers