Pre-Vanishing humans may start from PL 1 - 5. Most typically characters of heroic stature will start as either PL 3 or 4, with lower PL campaigns usaully involving characters that are regular people caught up in events far beyond them and PL 5 being reserved for the most exceptional characters, though higher power levels may be obtained through experience. Generally Pre-Vanishing humans may obtain a max power level of 8 and will generally only increase in power level with every twenty or more power points gained, though this may be waived in mixed campaigns
Post-Vanishing humans are often more powerful than there pre-vanishing counterparts, having a range of PL 3 - 8 for starting chatacters. They can generally attain a max power level of 15, though there may be exceptions.
Fictions have a wide variety of power levels, depending on their source material. Depending on the campaign characters that otherwise would be PL X plot device characters might have a set power level, or at least more defined characteristics with only a few X rank powers. With characters like SSJ 4 Gogeta whose to say that a particular NPC is too powerful to quantify?