In Pokemon Mystery Dungeon when you step into a monster house what is the best way to defeat it or run away from it. Also how can you avoid walking into one in the first place.
From my experience the best way to take on a monster house is to get into one of the narrow paths and attack it from there. This seams to be the best method as you are only fighting one Pokemon at a time and if you are running low on hp you can step back and swap with one of your team, you are also protected from the back by other members of your team.
The best way to run away from a monster house is to use a orb such as "Foe-fear orb" this will make all of the other Pokemon run away you should now use a "Illuminating orb" to reveal the floor plan, this will also show enemy Pokemon from the monster house you can now pick the safest path the the stairs.
I always keep a Petrify Orb or something similar with me in case of a monster house. It lets you pick off the monsters as you chose. I also keep at least one move like Wide Slash so I can hit several monsters at once.