So what’s in the tank now, I’ve lost track. Did you give up on the rummy’s?
The dwarf gourami is a much more peaceful choice than the angel, that should help things calm down though you may still have bickering amongst tetras if the schools are small. Especially the skirts; they can be very aggressive for their size. The good news, if you like the look of variety, is that white skirts, black skirts and glo tetras (specifically the “tetras” not the barbs or danios) are all the same species and will shoal together. So if you’re still having aggression from the skirts you could add a few of a different color morph and still meet the fishes schooling needs!