Grimserver |
While acid is the 3rd least resisted damage type (2nd is sonic and 1st is force btw) there are several kinds of monsters that are resistant or immune.
Outsiders of all types tend to have either immunity or resistance to acids, although it varies between creatures within a type (think daemon's and archons for type)
Several oozes are immune to acid, particularly those that deal acid damage.
As you mentioned dragons that deal acid are resistant or immune to it. Similarly, most monsters that deal acid are resistant or immune.
Acid elementals are a thing.
Generally though, acid is the best choice of the big 4 (electicity, cold, and fire being the others). Most of its spells are conjuration (instant) and SR No in addition to it dealing full damage to objects. For both access, utility, and damage acid is king.
Quandary |
Fyi, searching Paizo's PRD or d20pfsrd, or 3.5 SRD (which has better search tools... and most of the details carry over to PFRPG) is usually a good solution to any sort of question like this. If you are interested in only certain types of pages, e.g. bestiary entries, then include several terms that would always appear there, e.g. CR, Init to constrain the results to those pages... along with your terms of interest.