Aron may be based on the Pulgasari, a monster that eats iron in Korean legend.
-Bulbapedia
Lairon may be based on the Pulgasari, a monster that eats iron in Korean legend. It also has a similar body shape to the Placerias, a mammal-like reptile from the Triassic period.
-Bulbapedia
Aggron may be based on the Pulgasari, a monster that eats iron in Korean legend. It may also be based on a Triceratops and various therapods.
-Bulbapedia
So basically, a Pulgasari and a few reptiles.
