For what it's worth, there is a longish section called "Powered Characters versus Non-Powered Characters" in BRP that addresses this issue.
Some of the options presented are:
- Allowing the non-powered characters more skill points to construct their characters with. This head-start should prove decisive throughout a campaign.
- Allowing non-powered characters to invest in non-flashy powers like Defense, etc. that are technically powers but could be characterized in gameplay as "catlike reflexes, exceptional luck, etc."
- Allowing non-powered characters to invest "character points" into stuff like exceptional gear, etc. to help them compete.
Elsewhere in the book, I discuss the nature of balance and how it's the GM's job to make sure that a campaign is balanced.
For example, if you're running a criminal investigation scenario and one of the PCs is a police detective, he/she has a distinct advantage over the player who picked "student" or "priest" as their profession. There are some guidelines as to how to achieve this, but it's very general as that sort of stuff is intrinsically setting-specific.
Still elsewhere in the book are the Fate Point rules, allowing players to spend power points to affect dice results. This isn't a magic bullet to end the perceived problem, but given a finite number of power points, having non-powered characters using them to augment skill/combat rolls and having powered characters using them for powers seems to balance things considerably. (
Incidentally, this very problem is why I introduced the Fate Point system - giving non-powered characters something to do in gameplay with power points.)
Hope this helps.