In Monster Houses, I just attack the foes, usually with my Venusaur's Razor Leaf. My Typhlosion partner helps out with Flamethrower.
If I'm near a narrow hallway, I'll try to get as close to it as I can, so that I'm only facing one or two Pokemon at a time, instead of being ransacked (sp?) by five foes at once.
Other times, I make a run for the stairs if they're REALLY close by, though that occurs quite rarely. Also, I once exited the dungeon because the number of Pokemon in the Monster House was too overwhelming, as my other Pokemon had fainted.
~Aquarelle