You wait for the gym rework on things like this...If CP or some other number is still a factor in rankings, you have to see how this plays out...and adjust accordingly.
Niantic also knows about complaints on move rerolls so wait for that possible option if it comes out in 9 months, year, who knows...
Mid 2800CP won't last at all in my area so if the IVs are too low, there's nothing you can do to change and you might as well not power it up at all...