Male Blue prince holly
This holly was planted on the edge of my yard about 10 years ago. For the last 5 years it has steadily declined. I fear that it will be dead this spring as it has lost all of its leaves. A blue princess holly planted at the same time and about 10 feet away is magnificent. the deer like it so well I had to place construction fence barrier around it. What variety male holly can be planted nearby that will do well in heavy clay soil?
You can look for 'Blue Prince' or 'Blue Stallion' as pollinators. The latter supposedly flowers over a long time frame in the spring. In general, hollies grow best in moist well-drained soil. They do not like heavy poorly drained soils.
Perhaps you can improve the drainage in this area.