While only having a single type means that these creatures will not hit for double weakness often, it also means that those Pokémon will not be weak to as many things. From starter Pokémon evolutions ...

The most famous Pokémon card on this list and the centerpiece of any high-end collection, the 1999 First Edition Shadowless ...

Pokémon can be cute, kind, quirky, & mighty, but not all are very smart. Some, especially Psychic Pokémon, are geniuses, like Mew, Uxie, and Chansey.