I search the Irish Family History Foundation's online database at ROOTSIRELAND.IE. It has abt 20 M B/M/D, civil, census, etc records for most Irish counties. Records before 1863 are increasingly scarce - and almost non-existant before 1800.
For George, William, Robert, and John Pollock B on/abt the dates indicated, in all Ireland, I found 0 records. Since you state the family originated in Scotland, they were likely protestant. If so, these records are the least likely to have survived.