OHKO'ing defensive gliscor is excellent. I've run Houndoom on a few sun teams before. In dreamworld, he constantly revenged shandera or launched sun boosted STAB Fire blasts at incoming roopushin. At one point, I recall running taunt on him to keep him from being set up fodder (blaziken using you as setup when you're running a sun team is a gigantic pain in the rear, but +2 LO Timid Fire blast in the sun deals around 70-88% of Blaziken's hp if he attempts to set up). But I also recall HP Fighting handling those lousy heatran and tyranitar who didn't think you could touch them as well.
Sucker Punch or Pursuit/Crunch is a tough choice. Unless you catch him on the switch, you're always beat by gengar. He subs/disables crunch. He subs on the sucker punch. He focus blasts you. I generally found sucker punch to be better overall, since aside from burungeru (boil over is pretty pathetic even against houndoom), rankurusu, shinpora and scarfed pokemon, things rarely switch out from houndoom. I personally opted for sucker punch most of the time, nonetheless.
He was quite frail, but I ended up using him as a wall breaker, or an annoyance to walls with taunt, which works quite well with either pursuit OR sucker punch. I don't use him now because offense is everywhere and walls have dwindled from what I've seen. But in the future when the metagame irons itself out, I can definitely see him finding his place.
