Torbay (Torquay, Paignton and Brixham) has co-ed, Churston Ferrers Grammar School, and single sex, Torquay Girls' Grammar School and Torquay Boys' Grammar School, although the latter two are effectively on the same site and mix for some lessons in the higher years.
There is also Westlands School, which is not a grammar school but which has a selective "grammar" stream, and entry into this stream is via the 11+ for year 7 (useful perhaps if you have a "grammar-amenable" DC but also a "grammar-averse" DC, or multiples thereof). This 2015 link relates to Westlands but I stress that I have no personal experience of the school whatsoever, and so I can't comment on the newspaper report; http://www.torquayheraldexpress.co.uk/w ... story.html
When my DC took the Torbay 11+ at one of the single sex grammar schools, there were c.300 listed candidates on the day, and the PAN for that particular school was 150. N.B. the Torbay 11+ can be taken at any of the three grammar schools (gender relevance provided) but this does not need to be the first preference Torbay grammar school expressed on the subsequent CAF1. I believe that the ratio of approximately two candidates for each available place is relevant for each of the three Torbay grammar schools but that would need to be verified.
My DC passed the Torbay 11+, and is at their first preference Torbay grammar school.
Of the four other Devon grammar schools, I know next to nothing about the Plymouth grammar schools, nor about Colyton Grammar School in East Devon.