In a tank treated with copper DONT take any of the water with the fish. I also use a plastic acclimation container in the DT for many species of newbies and watch for any aggression.
I try to take the cooper out by doing water changes and running carbon. Cooper test reads .0
Questions is should i just scoop them out and into the DT or into a container with tank water just to make sure cooper washes off a bit more and then to DT ???.
What I would do is place them into a container and then drip them from the DT. Then when they've been accumulated to the DT water I would place them into a bucket with water just from the DT, then after a short while move them into the DT. I don't think you can ever make sure you got off all the copper but this way you should be able to get most of it off, and any that remains would be very small and not worth worrying about.