Faint Attack = Physical. Ditch it and put another Special attack back on. If you want Houndoom to special sweep, it needs a lot of Special attacks and little else. With Flamethrower and Dark Pulse, you have coverage against Grass, Ice, Bug, Steel, Psychic, and Ghost types. That's OK, but considering Houndoom's weaknesses to Water, Ground, Rock, and Fighting that remain, a Grass attack is more or less a mandate. That leaves you with 2 options: Sunnybeam, or more reliably, Hidden Power.

-Flamethrower
-Dark Pulse
-Sludge Bomb
-HP (Grass)

^My $0.02.