The problem is not making him too powerful or less powerful, IMO. What is important is that for any level of power, there must be the right amount of weakness. Think of the Green Lanterns... as much powerful they are, the original one was weak to anything made of wood, and the second one to anything yellow...
I am not saying that the wakness has to be something so literal... it could be something psychologycal... but there must be something that makes a superhuman character a lot less super.
Also, there are things that in a group writing environment are very difficult to do... for example, a character with mind reading abilities is actually impossible to write, because you should be able to read the mind of the other writers to do it justice... I know, as I wrote one in TOMB... the same could be applied for characters tied to mythologies that are not known by the other writers...
