Bodyweight challenges could be interesting. Things like seeing who can bench press/squat/deadlift their bodyweight for the most reps or, if you can't bp your bodyweight, go by percentage of bodyweight. Could be used for most exercises. Leaves two paths. You could lose weight to try and get an advantage, or just take the brute strength path and concentrate on lifting the bejeezus out of your bodyweight. You could even do an assessment in the beginning to see who makes the best improvement.
"Why yes, yes I am on a cutting diet. If you touch my food, I WILL cut you."
"We should ban treadmills instead of guns. I have never been harmed by a gun while treadmills, on the other hand, routinely make me feel like I am dying."
Gym pr's- bench 330, DL 405, squat 450
Meet pr's- bench 350, do 425, squat tbd