Everything you want to know about the ARENA is at the ARENA section. There have been ranked bouts, tournaments, and regular fights- just keep studying here. Be sure to officially join rank to be in ranked.

I think you can get a match in ranked if you just crave one thanks to a judge. If you have created a character specifically then you can just fight, or professionaly seek a judge to have them help organize.

There's also the PM option to spar with someone until ready. I hope I helped, fore I'm self-centered.