1. Start by marinating the chicken breasts. In a large bowl, combine the teriyaki sauce, garlic, soy sauce, ginger, and brown sugar. Add the chicken and coat well. Cover and refrigerate for at least 30 minutes, or up to 2 hours for a deeper flavor.
2. Preheat your grill to medium-high heat. Lightly oil the grill grates to prevent sticking.
3. Remove the chicken from the marinade and let any excess drip off. Season with salt and pepper.
4. Place the chicken on the grill, cooking for about 6-7 minutes per side, or until the internal temperature reaches 165°F.
5. While the chicken is grilling, brush the pineapple rings with olive oil and place them on the grill. Cook for about 2-3 minutes on each side until they have nice grill marks.
6. Once the chicken and pineapple are done, let the chicken rest for a few minutes before serving to lock in the juices.
7. Arrange the chicken on a platter, top each piece with a grilled pineapple ring, and garnish with chopped green onions.

One of the lessons I learned from my grandmother is to let the meat rest before serving to ensure it stays juicy and tender. Trust me, it makes all the difference!