I found that there really weren't many options. There is a Slugfest mode for a more arcade-style boxing match. For the normal boxing simulation, the modes are Exhibition, Career, and Classic Fights. You can also create a boxer. Basically, that's all. You can play around with the options a bit, but not much there either.
While in the game, your health bar and stamina meters are always in view. Also, the round number and time is in the bottom corner. Between rounds, they even have a scorecard to let you know how you're doing. The only real complaint I have with the game is the fact that it just runs slow. I understand with the detailed graphics and the smooth animations it can't run full speed, but it's boxing. It's supposed to be fast and furious. I think the game would be much more enjoyable if things were sped up a bit.
Perhaps to make up for the lack of realistic speed, they were careful to put in plenty of punches. Most boxing games put in the jab, cross, uppercut, and hook, but Knockout Kings 2000 goes the extra mile. There are dozens of combinations you can do. You can punch out of defense and even pull out some clutch punches. And of course, EA added some taunts and illegal moves (there is a head-butt, but no bite). Perhaps my favorite addition is the signature moves - the special moves that each boxer has. This adds a little variety to the match, as well as makes a name for your boxer.