Just going to drop in a comment here.

I've fought with and against guns and gun-like weapons, both on the low and high ends of the power scale, and it is possible to deal with them in all circumstances, provided you and your opponent can be reasonable about things.

One way is to have some means of blocking them.  Making a character immune to bullets or fast enough to dodge them would be too strong for mild-powers fights, but there can be stuff that defends against them.  An enchanted shield, for instance, could work to deflect them, while not providing an absolute defense.  I had one character who was essentially a big strong lizard-man, who relied on his scaly skin for protection... his scales weren't tough enough to take bullets in most areas, but the ones on his back were far tougher and had bony plates similar to a crocodilian, and so when he went down on all fours and kept his head low, most bullets would simply ricochet off his back.

The other way of handling things is by considering aim.  I actually got involved in a a fight recently between two unpowered humans dueling with guns in an obstacle-laden warehouse.  You'd think this would be over in an instant, since whichever character caught the other out of cover first would immediately win- but my opponent and I agreed that we'd take aim into consideration: a sudden shot at long range would not hit any vital organs, and would have a chance of missing entirely.  To land a lethal shot, we needed to either ambush the enemy and fire from up close, or figure out their location and line up a shot, while somehow ensuring the enemy didn't know they were being targeted.  

So IMO anything can work really, so long as both players willing to bend the rules a little if necessary.