"Assuming there are about 50 million Pathfinder players, one boar should be able to easily bring every character that has ever existed up to level 20."
It all starts on Archives of Nethys, an officially-sanctioned repository of PF2e’s material that Paizo generously supports. The Bristle Boar, originally intended to be a level 3 monster, is accidentally listed as level 83, making it by far the highest-level creature in the entire system.
How does the level impact things in it’s statblock?
It’s been a while since I played pathfinder