Pro matches are easy due to lighting, the amateur fights have very poor lighting. I like the canon 24-70 2.8 lens or for a budget maybe a Tamron 28-75 2.8 for these shots either way. Maybe a 50mm 1.4 prime lens for posed shots on your backup camera.
Google pics and see how pros shoot for amazing pics. Composition and the ability to see what will happen make the difference here. Learn more about the sport and what to look for as a boxer goes thru his or her moves.
Yes a towel is needed if you rind side, not only for your camera though LOL