My joystick has no pitch or roll in DCS World 2.5, only for the F-15C. I can assign functions to the buttons but I cant figure out how to get the pitch and roll to work. Any help would be appreciated.

Select the command line and then move your joystick so that DCS recognizes that axis for that command.

Make sure you un-bind those axis on other commands as well.
Read here

Thanks, I will give it a shot!!