I'm more inclined to opt for "captains". Don't want to have anyone feel like they are unable to actually battle, being a captain wouldn't mean you have to battle though. I'd certainly consider just hearing out all the captains a couple times a week for feedback.
And I'll probably adopt something akin to a tier ban similar to what @FraRPetO did for PZA2 in which each team can say no to a particular tier, but then after that I'll try and pick the most fairly matched tier between the two. Will probably implement some more intricate feedback system to select tiers with the captains input, but