It is not known to evolve into or from any other Pokémon.
Dedenne using its whiskers to communicate
Dedenne is a bipedal, orange mouse-like Pokémon with a round body. It has round, black ears with pale yellow interiors, black eyes, a tiny nose, and a prominent upper incisor with a slight point. On each cheek is a circular, dark orange marking with two black whiskers. The upper whiskers have branches and resemble antennae, while the lower whiskers are simple. There is a thick black stripe down is back and it has a pale yellow belly. It has stubby limbs with three digits on each paw and a long, thin black tail with a tuft of fur on the tip.
Dedenne's upper whiskers serve as antennae that can send and receive electrical waves. This allows it to communicate with others of its kind over great distances and sense its surroundings. The simple, lower whiskers are organs that can fire electricity. It absorbs electricity from buildings by plugging its tail into outlets.
NA: This Electric/Fairy-type Pokémon's round shape and antennae-like whiskers make it very distinctive. It has a habit of sticking its tail into sockets to absorb electricity. Its Discharge attack shoots off in four directions, passing through obstacles and stunning any fighters it hits along the way.
PAL: This Electric- and Fairy-type Pokémon's round shape and antennae-like whiskers make it very distinctive. It has a habit of sticking its tail into sockets to absorb electricity that it fires from its whiskers. Its Discharge attack shoots off in four directions, passing through obstacles and stunning any fighters it hits along the way.
Dedenne may also be based on the French version of the tooth fairy (La Petite Souris; i.e. The Little Mouse), which is described as a small mouse that exchanges baby teeth for coins, hence the Fairy typing.
Dedenne may be a combination of 電気 denki (electricity) and antenne (French for antenna).