Use a piece of pipe or a large flex handle inserted through one of the holes in the wheel, and find something to pry against, like the hub.
Jerk the tool hard against the rim, using your pry point as a solid point.
This can be a real PITA.
Kicking or stomping around the edges of the tire sidewall will usually work.
I had to remove a wheel from the older Subaru in February, which had last been removed in October.
Even after only four months, it was absurdly hard to break loose.