Need help sexing my pleco please

[kin11470]

Any idea for my pleco sexing?
I got 9 of them.

[Mol_PMB]

A general principle is that a male is usually widest at the 'shoulders' and tapers back in a triangular shape from there. A female bulges further back.
This rule doesn't always work (especially with under or over-fed fish) but it's fairly reliable.
Based on that, in the group photo, the large one on the left hand side is a female. Probably also the one just below it and the darker one on the right hand side. The single fish in the top photo is male; I think most of the others are although there's a couple not so clear.