.....................Damnit, I was hoping to keep it a secret.
They must be adaptable, able to quickly adjust when the total shitstorm of the awakening occurs, which is why the man in silver throws a spanner in the works of each potential champions life, to test them. the trial he engineers for each group is meant to strengthen them and gain them credibility so the world will be wiling to follow. In addition, they need to be the sort of people the world can rally behind, be it because of their strength, leadership ability, or even just because they are trustworthy.
I was hoping to be all super-cryptic about it, but you have a point.