Complex sentence: Both catch wrestling and Greco-Roman were popular, and legitimate amateur and professional sports until the late 1800s, when catch wrestling changed slowly into the sport known worldwide as pro-wrestling, recognized more for its theatrical antics and entertainment than wrestling ability.
Split into simpler sentences: Both catch wrestling and Greco-Roman were popular, and completely legitimate amateur and professional sports. But, from the late 1800s onwards, a sub-secton of catch wrestling changed slowly into the sport known worldwide as pro-wrestling, recognized as much for its theatrical antics and entertainment as wrestling ability.