A charcoal grey or black tuxedo would look very nice with a champagne colored wedding gown. You can often order the grooms accessories in matching or complimentary colors.
The groom should wear a tux. It doesn't matter which color it is since you're already going with a non-traditional dress. You don't have to worry about if it's traditional or not. It's your wedding do what YOU WANT.
wedding to be informal groom will not be wearing a tuxedo any other color options add a comment