In a small bowl, whisk together the teriyaki sauce and garlic. Lightly spray a baking pan with cooking spray. Place the grouper fillets in the pan. Brush the teriyaki marinade on both sides of the fillets. Cover and refrigerate for at least 15 minutes to marinate the fish.
Heat the broiler (grill). Position the rack 4 inches from the heat source. Broil (grill) until the fish is opaque throughout when tested with a tip of a knife, about 5 to 10 minutes. Remove from the broiler. Squeeze 1 lemon wedge over each fillet and then sprinkle with Italian seasoning. Serve immediately.