Answer 1

No, Legendaries and few other pokemon are in the 'No Egg' group, which means they cannot breed, even with Ditto.

Comments

The only legendary you can breed is Zorua*

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Not a legendary.

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You can breed Rotom.

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Rotom isn't a legendary either. The only legendary that can breed is Manaphy/Phione.

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I have solid evidence. In Sapphire, I put a Rayquaza and a Ditto in the Daycare and YES, I did recieve a Level 5 Rayquaza. Maybe it was a glitch, but I've had it for like, two years now.

Answer 2

You can breed manaphy

Comments

and phione :)

Answer 3

Any pokemon in the undiscovered egg group you can't breed so the only leagendarys you can breed are rotom, manaphy, and phione

Comments

Technically, Rotom isn't a Legendary Pokemon. You can recieve it several different ways, and in Diamond, you can see people with Rotoms.