The nemesis must fit as a shadow-archtype as opposed to simply being a major antagonist
I'll try to keep the gauntlet in order but I am not an expert on every character. If the gauntlet happens to include the duo you wanted to use, just remove them from the gauntlet and see how far they get.
Your duo gets 1 day prep between each round and full healing, the gauntlet characters do not get any prep, but they do get teamwork.
All are in character and have limited knowledge (what they might logically have access to if they were in the same setting)
PS: Don't underestimate Oz and Cheshire because of where I placed them. They kick ABC logic right out the window.