Lillipup are known for their ability to determine at a sniff if enemy pokemon are weaker or stronger, and choose whether or not to battle accordingly, an ability few pokemon share. For most of the species, this ability is a great asset which allows them to avoid battle with the few strong pokemon in the areas where they are typically born. Newborn Lillipup are noted for being especially common on the routes leading away from Nuvema Town, a location also favored by beginner trainers because of the relative weakness of the local fauna. Typically, a single Lillipup will travel Unova as it ages, in search of evenly matched opposition, and return to the Nuvema area only to lay its eggs.
Yet wild Lillipup have often been called cowardly, for rather than accepting a truly even match or battling as a slight underdog, they will only seek battle if they believe their opponent to be at least slightly weaker. Most Lillipup can at least claim to be stronger than other species of newborn pokemon at birth, but a few are too small to even claim that modicum of power. These runt Lillipup can continue to look like newborns for a period of months, for although they can find sustenance in the wild, victory in battle is a requirement for any Lillipup to grow in size and strength, and one can not be victorious in a battle that never begins.
When humans enter the picture, the equation these Lillipup use changes, for battles with human trainers offer not only victory or defeat, but capture and the prospect of growing stronger with teammates under the tutelage of a master. For this reason, they eagerly challenge human trainers to battle, and are considered to be among the easiest pokemon for beginner trainers to catch.