Q.My House Foundation Has A 25 Degree Downward Slope. What Foundation Plants Should I Use?
The area faces east, but has shade trees.

Certified GKH Gardening Expert
You have quite a few options available to you! Here are some articles that will give you some suggestions:
https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-6/zone-6-native-plants.htm
https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-5/zone-5-shade-plants.htm
https://www.gardeningknowhow.com/plant-problems/environmental/plants-for-erosion-control.htm
https://www.gardeningknowhow.com/special/slope-hill/hill-ground-cover.htm
https://www.gardeningknowhow.com/special/slope-hill/plants-that-grow-on-slopes.htm