Houndour and houndoom work well in a deck.  I would highly recommend you make a deck with these cards.  I would choose to put in the rare houndour more then the uncommon one but it is your choice.  Well anyway here is my strategies combos and some other things I think you might need.
Houndour (39/75)
Type: Dark
40 Hp
Bite
Energy cost: 1 colorless energy
Base Damage-10
Plunder
Energy cost: 1 dark and 1 colorless energy
Base damage: 10
Before doing damage, discard all Trainer cards attached to the defending pokemon (before they affect the damage)
Weakness: None
Resistance: Psychic
retreat cost: 1 Colorless energy
 
Houndour (rare and holo version)
Type: Fire
50 hp
Smog
energy cost: 1 fire energy
base damage: 10
Flip a coin.  If heads, the Defending pokemon is now Poisoned.

Collect Fire
Base damage: 20
if there are any fire energy cards in your discard pile choose one of them and attach it to houndour
Weakness: Water
Resistance: None
Retreat cost: 1 Colorless energy
 
Houndoom
Type: Dark
70 hp
Crunch
Energy cost: 1 Dark and 1 colorless energy
Until the end of your opponents next turn if an attack damages the defending pokemon after applying weakness and resistance that attack does 20 more damage.
Flamethrower
energy cost: 2 fire and 1 colorless energy
base damage: 50
Discard one energy card attached to Houndoom or this attack does nothing.
Weakness: None
Resistance: Psychic
Retreat Cost: 1 colorless energy
The uncommon houndour belongs in removal decks but watch out he only has 40 hp
The rare houndour belongs in any deck with houndoom he is the best of the two houndour by far.  He has 50 hp witch really helps and he also has collect fire attack to get the fire energy on hem and pre-par for flamethrower attack.
This is a combo I found with this card.  First turn houndour is out and you have a dark energy in your hand a computer search,  fire, energy, and a quilava. You computer search discarding 2 fire energy and finding a houndoom.  attach an energy and use smog.  The nezt turn you attach an energy and use collect fire.  He now has 3 energy on hem and you are done with turn 2.  Next turn you evolve attach a dark energy and use crunch or flamethrower.  So basically you use the discard of the energy to your advantage to power up houndour and get houndour out.
Once you have houndoom out you should use crunch (unless flamethrower will ko hem and crunch won't).  Then the next turn you can whip out 70 damage with flamethrower and add 10 cause of dark energy (unless crunch will ko hem this turn cause you want to save those energy if you can). 
Now you should now the other cards you should put in a deck like with these cards.  You should think about putting in some basic fire type pokemon like magmar, and entei.  You would also need cleffa.  You might want a sneasel
On trainers you will need ecogym, bill, computer search, elm, gold berry, potion, oak, plus power defender, and gust of wind
As for energy you should have about a total of 20 energy, 4 dark, and the rest fire
I hope these tips are helpful to you if you would like to comment on my post, need help on a card about something, want me to repair a deck, want to look at some of my decks, please e-mail me at losernumber8@msn.com
 




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