Strychnine is the most popular stimulant. It provides the energy to fight despite multiple puncture wounds. It's legal in Oklahoma, Louisiana, and all but nine of New Mexico's counties. Birds are angered by being held in each other's faces at the start of the fight, as well as whenever they stop fighting, thus preventing them from submitting. Along with the blades and stimulants, this makes cockfighting anything but natural.
Boxers have a choice whether to fight and can call it quits when they choose.
Instead of blades, they wear padded gloves. Referees try to stop a match if a boxer is getting seriously hurt. In cockfights, the roosters are armed, drugged, and goaded to fight to the death. We have no interest in character attack. What cockfighters do to animals and the children they expose to the cruelty is our concern, not who they are.