The second most common type of Pokemon, Normal-Types tend to be either mammalian or avian in nature, though a not insignificant smattering of unique species can be found amongst their ranks. Normals are considered the "default" pokemon type, and there is evidence to suggest such a viewpoint; where all other types specialize in their field to a high degree, normal types are jacks of all stats with some species having a "gimmicky" ability. Their flexibility, however, comes at the cost of integration; the majority of Normal-Types are pure and of the hybrid types only five are not half flying.
Aside from species-specific gimmicks, normal types have only their intellect as an advantage. However, it is an advantage they use to great effect, able to assault any foe with equal ingenuity and skill. Their weakness against both Steel and Rock type opponents is only a result of the type's natural armor, and while none of their usual moves can affect ghost types, the same is true in reverse; due to their extremely level-minded nature, most ghost-types cannot directly scare them with their usual methods. Only Fighting types can outwit them in combat, or out-fight them, due to a Fighting-type's specialization in close combat.
Non-gimmicky Normal Types are generally mammalian in nature, although Normal-Flying types trend toward more avian builds. Beyond that, there is little similarity in morphology; in fact, a number of individual species break the mammalian trend for the sake of their individual natures.