The one on the lower left looks like a RES.
Here is a link with a good picture of a GSF.
GSF Click on the picture for a better look and there is also a second picture. Notice the mouth. The corner of the closed mouth extends all the way back to the front of the fishes eye. In your larger size fish the two that look like GSF characteristics do not have that mouth. The mouth is smaller. That and the fact the fish looks taller in relation to its length compared to a GSF makes me think the two larger fish are hybrids.
Now the pictures of the small fish (2-3" long) from a previous post, those look more like pure GSF. So you may have contamination from some pure GSF at some point and that is their reproduction. That might or might not become a problem, depending on how strong the establishment of your other fish are. If they have a good running start ahead of the GSF, it might not be much of an issue. If there is tons of GSF fry that eat all the other fish recruitment fry or eggs, it can be a real problem, so I'm told. Esshup has a story of a clients pond over run by GSF that did not allow other fish recruitment.
Dave Davidson actually likes to have some GSF in his southern pond. So not everyone thinks they are such a bad deal. Just almost everyone.
