Krokling's icon is the same as the one that's used for monstrous Pokemon in Generation I.
Its dex entry references the canon Pokemon, Larvitar's dex entires where the Pokedex talks about Larvitar eating mountains.
Krokling is based on one of the Gen 1 box sprites, resembling something that looks like a walking crocodile with a horn. This is based upon the groups of people who are obsessed with Generation I, known as Genwunners. It also bears a resemblance to Rhydon's original design. Its shiny coloration is meant to mimic the look of the Generation I sprites when the games are played on a Game Boy Color.
Krokling is a combination of a corruption of crocodile and -ling, a suffix commonly used to describe baby animals.