Normal maps are generated from whatever high frequency detail you create with any of the sculpting brushes. That being said, they and height (displacement) maps tend to work best when the detail, relative to base is mostly straight up from each face of the base model from which the detail is projected (either by the illusion of a normal map or by micro-poly displacement of geometry built at render time.)
This means that when you use brush’s that tend “slew” or shove detail along the surface relative to the base model, instead of build upward or downward from the surface (that is, in the direction of the normal of the surface polygon) you may get more problematic results, though most mapping algorithms, including Zbrush’s map generators tend to be pretty good at giving you a decent normal or displacement map under most conditions.
The most problematic brush for you would likely be the snake-hook brush when you’re pulling geometry at deep angles to the surface of the base mesh or even looping over the base mesh. Neither displacement nor normal maps work well in this situation and the only solution are various forms of vector maps which not only encode displacement relative to the up-down nature of the surface polygon, but also encode at what angle (e.g. the “vector”) relative to that surface the detail geometry is to be displaced.
Long answer to a simple question, but in general, you are safe using all of ZB’s sculpting brushes to make normal-mapped models–the real key is not the brush, but how it is used. Try to make surface detail build up or push into the general shape of your base mesh and you’ll be fine. Try not to pull displacements across the surface as this becomes harder for typical normal-map or displacement map renderers to deal with.
HTH,
-K
