You could do a point system, not sure how easy it would be to keep track of, but kind of like.
You pick a fighter and then a confidence number afterwards. The person with the most points wins the pickem.
Pretty standard, like below.
Fight 1: Fighter A - 3 points
Fight 2: Fighter A 4 points
Fight 3: Fighter B 2 points
Fight 4: Fighter B 1 point
Fight 5: Fighter A 5 points
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* B8 LNC *
*****es be crazy!!