In blender, combine green onions, garlic, orange juice, all but 3 tablespoons oil, lime juice, cilantro, cumin and hot sauce. Blend until all ingredients are finely chopped and well combined.
Place chicken, pork and shrimp in separate large zip-top plastic bags. Evenly pour marinade into each bag. Seal bags, pressing out excess air. Massage ingredients in bags to combine. Refrigerate 2 to 4 hours to marinate.
Cover grill rack with aluminum foil; with fork, poke several holes in foil. Prepare outdoor grill for direct grilling over medium-high heat. In large bowl, toss bell peppers, red onions, 1 teaspoon salt, 1 teaspoon pepper and remaining 3 tablespoons oil.
Place shrimp on 1 side of foil-covered grill rack and bell pepper mixture on other side. Cover and cook shrimp 4 to 5 minutes or until shrimp turn opaque throughout and reach an internal temperature of 145°. Remove shrimp from grill; keep warm. Stir
Remove foil from grill rack. Place chicken and pork on hot grill rack. Cover and cook chicken 10 to 12 minutes or until chicken loses its pink color throughout and internal temperature reaches 165°; cook pork 6 to 8 minutes or until internal temperat
On microwave-safe plate, place tortillas between 2 damp paper towels; heat in microwave oven on high 35 to 45 seconds or until tortillas are warmed.
Thinly slice chicken and pork; transfer to large platter with shrimp. Place bell pepper mixture and toppings, if desired, in separate serving bowls and serve with warmed tortillas.