Place the sliced onions in the bottom of the slow cooker. Pat the pork down with paper towels, set it aside.
In a small bowl, mix together the garlic powder, onion powder, brown sugar, paprika, salt, and pepper. Rub the seasoning all over the pork, use it all.
Place the pork on top of the onions, cover, and cook on low for 8 hours or until the internal temperature reaches 200°F or the meat easily shreds with a fork.
Take the pork out and remove any bones and excess fat, shred the meat and add it back to the slow cooker to mix with the cooked onions and liquid. Now you can use the pork as is on sandwiches with some bbq sauce or in any recipes called for pulled pork.
Notes
Either portion of the pork shoulder will work the Boston butt or the picnic roast.
This can be served in a variety of dishes, this is just a basic pulled pork recipe, do with it what you like.
This can be frozen for later, see my tips above on how to do that.
Use the simple rub recipe I provided or make your own or even purchased rubs will work.
Make sure you cook this on low, the is how it will shed nice and easy, this should not be cooked on high.