You can't. It's impossible to get legendary Pokemon eggs except you could get Phione by putting Ditto and Manaphy together. It's only for Phione because there's no other way to get Phione unless you find an Action Replay code for it. So basically, you can't get legendary Pokemon eggs. You could try putting a legendary Pokemon and Ditto together, but it won't work.
Dialga and Palkia are the legendary Pokemon mascots of Pokemon Diamond and Pearl respectively. As they are legendary Pokemon, they cannot be bred to produce eggs.
You can breed Manaphy with a Ditto to get Phione.
all except for legendary rotom, manaphy, and maybe latios and latias can mate
the item legendary diamond legendary diamond legendary diamond
it is impossible except for when you have cheats in Pokemon pearl,platinum,diamond
the legendary Pokemon in diamond and pearl are dialga and palkia.
No, a Bidoof cannot evolve into any Legendary Pokémon in Diamond.
it is not possible as legendary Pokemon are not breedable
Dialga
The only legendary that can be in an Egg is Phione, which you need to breed Manaphy with a Ditto. But other than that, you can't get any Legendary Eggs.
you can catch a ditto and put it in the daycare with a giratina and the they will make the egg. have fun
arceus