Puffers in general are very sensitive to ionic and chelated copper. Not saying some or even most won't take it but there have been quite a few complications with using copper. CP would be the go to for puffers and it treats almost everything besides bacterial infections.
I own quite a few wrasses who are also sensitive to ionic copper, I treated all with no ill effects, my lineatus was thrown right into therapeutic because of a velvet scare and is doing fine. If you do use copper, just ramp it up very slowly and watch the fish. Take a week to do it.
If you're local to Pa, I have some CP if you can't find it.