For a casual or small time, pastime, or between just friends or a known person, they can do cockfighting without the need for any paper or documents.

For legally operated cockfighting arenas where fights happened regularly like an everyday operation, those cocks should be registered with their official breeders. They can't just go there and put their cocks on the fight to earn money.

Since it's business, the organizers are paying taxes, as usual, that's why authorities shut down those operations that are running under the shadows.