Keen Eye is an ability found in various animals of different types.
In Battle Use[]
Animals with the Keen Eye ability cannot have their accuracy lowered.
Out of Battle Use[]
Animals of lower levels will not be encountered when an animal with the Keen Eye ability is out of its aniball.
Speculation[]
Keen Eye likely developed from animals with powerful visionary abilities likely from either spotting prey as a predator or using sight to scout out for oncoming predators.