If so, would I just need a Ditto?
One can.
Any Pokemon from the Undiscovered Egg Group, legendary or not, cannot breed.
The prime example is Manaphy. Manaphy can in fact breed with Ditto. However, the result is Phione. Phione cannot evolve into Manaphy.
No its not possible
How to change your username How to add a user avatar Why was my post hidden? Question etiquette Flags vs Downvotes Anime FAQ Official PokemonDb League
Type a Pokemon name, type, move or ability to see instant results.