I think the subject and material should be a surprise. Adds to the challenge and intrigue in a competition. If one or two partcipants' suggestions are used doesn't that give them an advantage? A competition where the ground rules and tests are regulated by a neutral third party is best, and the mystery of not knowing the material can reveal alot about peoples' strengths/weaknesses.

Like when they unveil the "key ingredient" in Iron Chef. Knocking all the contestants to the floor in surprise makes even ground for a race.

That being said, I wonder who we could get to be a neutral 3rd party regulator? I for one would love to have Y or Mutachi as a surprise supervisor. God knows putting Terra or Assertn in charge of this might lead to calamity... but, since I don't know shit about shat I could almost care less who decides or what they choose, so long as it's done neutrally.