So I would go for the noxius idea. Basically make a scenario which is the same as the Primus Superiorum scenario in the rulebook, with two titan-rounds in the beginning, and one final round. The difference would be that instead of titans, each cohort has to battle a group of "lesser" noxii. I'm thinking a number of noxii equal to the number of gladiators they are fighting plus one. And for stats, I am thinking that a noxius would be like the character Noxius, except with only five generic vitality points. And the opponent playing the noxius cohort has no favor, and can gain no favor.
That seems interesting, but it might get a little boring for the opponent to play a whole round with weaker Noxii... although he is a beast (metaphorically)