everything but bucket and skates. i washed my **** all the time and never hurt it. just make sure there is as minimal amounts of plastic in there as possible. don't put shins in there with the outer shell... i learned that the hard way lol.
Sometimes equipment will state on a tag what it can handle. i use Farrell shoulder pads and it clearly states to machine wash and hang dry because the dryer can hurt the foam stuff and nylon meshing it is held in with.
Some stuff may shrink like the glove palms made of leather. You do NOT want that to happen.
If you have the heat on you can place things near enough to the heater vent to dry out too. I lay stuff on the floor in front of a couple of heating vents here and it does the trick without damaging anything.
I think the best thing to do is not let it sit out in the rain!