Complex sentence: Halsey attended Rancho Buena Vista High School where he competed in wrestling and excelled, he currently holds the best overall high school record in school history with 150-16 and 80 pins, and also won a California high school state championship.
Split into simpler sentences: Halsey attended Rancho Buena Vista High School where he competed in wrestling and excelled. He currently holds the best overall high school record in school history with 150-16 and 80 pins, and also won a California high school state championship.