You guys do realize they aren't necessarily talking about here right? It could easily be for writing, or some other RP site.
Anyways, part 2 of the only person ACTUALLY trying to answer the question.
For the sake of balance, just look at the games, or at least the abilities. Your character needs to be beatable, so for example don't give them a full list of nulls, that's lame. They should do well with one or two things, and struggle in another area.