All Plymouth Rocks are to have yellow feet and legs. Females may have some dusky color over lay but under line color must be yellow. Eyes are to be bright red not orange or yellow. Breaks are to be horn color going to yellow.
The barring needs to be crisp and straight across, not chevron. That is the biggest thing other than the correct body type. It's rare to see show quality BRs, especially in standard size. Find a Standard of Perfection and check out the description.