If you compete in a KCBS certified competition you will cook the four meat classes - ribs, brisket, pork, chicken. There could be others, and sides or salsa, depending on the individual competition and their rules.
Generally the meat lineup most competitors cook for a comp. is -
6 slabs of ribs, most use babybacks- 2 briskets- 2 butts- 20 or so chicken thighs. That gives you some choices and backup.
There are advantages to cooking brisket and chicken at higher temps. The chicken cooked at 350° will have a crisp skin and you want that instead of the rubbery skin. The brisket will not take near as long at 285° and will turn out fine. Cook to temperature.
These things more or less dictate more than one smoker so you can run different temps. You can have a main smoker cooking ribs and butts at 225-250°, and do the chicken on a bullet smoker or drum at 350°. Same for the brisket at 285°.
Thing is, you best do several trial cooks in the driveway to see how long the different meats take to cook and to get your routine down.
You might talk to Tonto1117, Bud'sBBQ, or BBQBubba about this, they are a seasoned comp. cooking team, The Smokin' Scotsmen Competition BBQ Team.
And thoroughly read and know the rules. You can't play the game if you don't know the rules.
Oh yeah, brisket is probably the hardest meat to smoke for competition. Butt is easy, you generally can't kill a butt.