Place pork chops, 1/2 the bottle of teriyaki sauce (eyeball it), and the reserved pineapple juice in a large plastic container, stirring to coat.
Set aside to marinate for 10 minutes. If you have longer, then up to 2 hours is perfect!
In the meantime, combine garlic powder, salt, and pepper in a small bowl.
Remove pork chops from marinade, and discard marinade.
Sprinkle pork chops evenly with seasoning.
Grill the pork chops for 4-5 minutes on each side on a gas grill, basting them with the remaining terikyaki sauce.
Cook until a meat thermometer reads at least 145 degrees.
Let pork stand 5 minutes before serving.
Grill pineapple slices for about 1 minute on each side.
Serve pineapple slices over pork. Enjoy!