How do you get a houndoom in Pokemon Pearl?

you can go onto Pokemon emerald and catch it then go onto pearl, beat the elite 4 and then next time you turn on the game instead of hitting continue hit migrate from emerald... but you have to make sure the Pokemon is not in your party box. then you can migrate it and after that go to the bottem of your pearl map and fly to that green dot play the game and you will find your 6 Pokemon in it. when you do in those six Pokemon will be your peokmon you wanted

You can also use the poke searcher thing just outside of lake valor