What is the name of a combat sport in which nearly all holds and tactics are permitted?

Catch wrestling (originally Catch-as-catch-can) is a classical hybrid grappling style and combat sport. It was developed by J. G. Chambers in Britain c. 1870. It was popularised by wrestlers of travelling funfairs who developed their own submission holds, or "hooks", into their wrestling to increase their effectiveness against their opponents. The training of some modern submission wrestlers, professional wrestlers and mixed martial artists is founded in catch wrestling.

Catch-as-catch-can wrestling, basic wrestling style in which nearly all holds and tactics are permitted in both upright and ground wrestling. Rules usually forbid only actions that may injure an opponent, such as strangling, kicking, gouging, and hitting with a closed fist. The object is to force the opponent into a position in which both shoulders touch the ground at the same time. Formerly known as the Lancashire style in England, catch-as-catch-can became the most popular form of wrestling in Great Britain and the United States and, with slight modifications, was introduced into Olympic and international competition as freestyle wrestling.