The best solution depends on the amount and length of slope, whether the supports are fixed or sliding, etc. Angled pipe shoes are supplied for small quantities, but they are generally avoided for larger quantities due to the variety of different sizes involved, and the extra cost. Roller supports can be a good solution. If suspended supports can be used then rods and clamps (with or without spring supports) offer another solution, with the movement of the clamp on the rod making allowance for the slope of the pipe.