If you have a question that is not answered here, please comment with it.
1. Do not write using someone else's characters unless explicit permission is given to do so.
2. Powers manifest ('start') between the ages of twenty and twenty-seven, unless the power is a physical one. Such changes are present from birth, e.g. gills, or develop during puberty, e.g. poison glands beginning to work.
3. The first power manifested in 1921. For a fandom to be used in this world, the desired character(s) must have been born in or after 1894.
4. A rough estimate of the amount of powers in the world's population is 25%. Exact numbers are impossible to determine.
5. Characters are not allowed to have noncongruent powers. Telepathy and empathy are congruent; telepathy and telekinesis are not.
5a. Physicals never have additional powers.
6. As the fandoms are set in the same world, they are not forms of media. Rob Gordon cannot watch CSI, and Gil Grissom cannot read or watch High Fidelity. However, just because they are set on the same planet does not mean the characters will necessarily interact with each other.
7. Fandoms must take place in the 'real world.' Star Wars cannot be used, but Law & Order can.
8. Unless medicated or surgically altered, powers are stable for their entire lives. There is no way to turn a power into a normal. In some circumstances, powers may fluctuate, but they will never disappear completely.
9. No "comic book" powers may be used. For example, there is no teleporting, or flying except by anatomical means.
9a. Humans cannot grow feathers or shapeshift to the point of altering bone structure and major organs.
10. If you cannot explain a character's power using shady physics arguments or medical explanations, then you probably should not give it to them.