GC can definitely be used instead of prazipro. It "should" work about the same, the concentration of praziquantel is slightly lower in GC than Prazipro. I know they say Wrasse are sensitive to Praziquantel, I have not experienced this at all using either GC or Prazipro as long as dosed per instructions.
RRR should not be mixed with copper and other meds. It may provide some temporary relief for some parasites used as a bath prior to treatment. Also helps to prevent secondary infections in afflicted fish. No need to combine it with the others anyway as long as you are using a method deemed effective.
The trifecta is to be used dosed into water column. To treat for bacterial infections.
If you are going to transfer fish to clean sterile QT after 14 days of copper the only other treatment you will need prophylactically is food soaked with GC/focus (GC or metro/focus soaked food can be done during copper if you would like. I do it as soon as they are eating and settled into QT, especially with wrasse) and a deworming treatment of GC or Prazipro.
I would not recommend exposing the fish to the trifecta or any antibiotics for that matter prophylactically. Only use if you have a known bacterial infection going on.
Awesome, thank you for the info!
Can GC be dosed directly in the water instead and still have the same effect or does it need to be used on the food?