Dominant pedals are the most common type and a range of consonant and dissonant chords can be played over them. Most of these chords work best when they resolve each time onto some sort of V chord before going onto another one.
Diatonic / consonant
These chords can be used freely (they are not dissonant so are not technically pedal harmonies).
In this example the home key is C MAJOR. Dominant sevenths are treated as if they are consonant but try to resolve the seventh by step downwards if the music continues from a V7. The dominant minor 9th at the end is an extension of the dominant and the 9th must resolve down by step.
Dissonant / chromatic
Some of these are seriously dissonant and need careful resolution. Each chord individually needs to resolve back to the original chord V (in this case G) as shown before moving to another one. These examples are again on the dominant of C MAJOR.
Rising thirds / sixths
These are the main diatonic and chromatic passing notes that work in thirds or sixths. They can also work as auxiliaries. The bracketed ones are dissonances and must be resolved by step to one of the non-bracketed ones. Example on the dominant of C MAJOR.