Complex sentence: Billy Simmonds is a competitive Powerlifter with the worldwide organization the IPF, the largest Powerlifting organization in the world, which follows the IOC and WADA drug testing standards.
Split into simpler sentences: Billy Simmonds is a competitive Powerlifter with the worldwide organization the IPF. The IPF is the largest Powerlifting organization in the world and also follows the IOC and WADA drug testing standards.