D/P Pokemon in FR,LG R S E?

Would it be possible to add D/P pokmn to The 3rd generations?

Yes. Many people have done it.

yeah, a lot of hacks have done it.
You have to use UNLZ gba.

Unlz GBA, RS Ball, Pokemon Amplifier, and Pokemon Editor Pro are all you need to insert D/P Pokemon.

were can iget all these programs as people jus talk about them but don't hav links

Download either from the Toolbox thread here, or some other ROM Hacking Site.

You can download mostly all of those tools from WAH, or if you know any others then do that. But I suggest WAH (Whack a Hack) to be your best resource-finding website to go to if you need help, tools, guides, and other stuff.

Hope that helps.