Okay, sorry if I took you're job UnderXRay, because you didn't specify the Secret ID, I made it the reverse of your Trainer ID. This means that the Secret ID of the Dunsparce is 10333.
I don't know the relation to the Friend Code. So if you still want the Friend Code part to be with your Dunsparce, I recommend you wait for UnderXRay's code that he gives you.
Activation: Press L and R together. Once you press those two buttons on your DS/DSi it will replace the 2nd Pokemon in your party. You must have at least two pokemon in your party for this code to work. So I recommend putting a not-needed pokemon on the 2nd Slot of your party. This way, no useful pokemon would be replaced. It is also recommended that after you get the Dunsparce, save the game then turn off. This is because if you accidentally press L and R again, you will activate the code a second time, replacing the 2nd Slot of your party an extra time.
Dunsparce (Diamond Only):