Although travelers to Kalos have long told rumors about unusual-looking creatures resembling Zubat or Woobat, but with large, golden eyes, it is not until the advent of mechanization that any records can be found containing the name "Noibat" or the idea that the bats with these eyes comprise a different species of pokemon. Noise pollution has effected the lifestyles of many echolocating pokemon, but it is only the Noibat who so dramatically adapted to these conditions. They did this both by developing far superior eyesight to the majority of cave pokemon, to account for the reduced value of their hearing, and by becoming even louder than the machines which disrupted their habitat – so loud that their echolocation became as much a deadly weapon as a means to perceive the world around them.
Noibat succeeded in turning the tables – for although a single troublesome pokemon could be captured or driven off, a flock of bats as numerous as Kanto's Zubat and louder than a jackhammer created unacceptable working conditions for anyone near their caves. The advent of the Noibat coincided with mass resignations and emigration from their habitat, and efforts to transfer people there were met with immediate strikes.
Evolution, however, does not reverse itself when the stresses which put it in motion disappear. Although there is nothing left to drown out, save perhaps the echolocation of quieter bat pokemon, Noibat remain as loud as ever, and their noise pollution has stressed their neighboring pokemon far more than the humans ever had. When Noibat encounter humans today, it is as trainers seeking the power of their evolved form, or as researchers seeking to better understand species (as opposed to individual) evolution by studying its newest example.