Preheat the oven to 375°F.
In a large skillet over medium heat, cook the ground chicken until browned and cooked through, about 5-7 minutes.
Stir in the cooked rice, diced pineapple, teriyaki sauce, soy sauce, garlic powder, and ginger powder. Cook for an additional 3-4 minutes until heated through.
While the mixture is cooking, slice the tops off the bell peppers and remove the seeds and membranes.
Stuff each bell pepper with the chicken and rice mixture, pressing down gently to pack it in.
Place the stuffed peppers upright in a baking dish.
Cover the dish with aluminum foil and bake for 25 minutes.
Remove the foil, sprinkle shredded mozzarella cheese on top of each pepper, and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Garnish with sliced green onions before serving.