Minun

Minun is a Pokémon which is best when battling with Plusle in a Double Battle, when battling on its own, it is much weaker.

Ruby
Minun is more concerned about cheering on its partners than its own safety. It shorts out the electricity in its body to create brilliant showers of sparks to cheer on its teammates.

Sapphire
MINUN loves to cheer on its partner in battle. It gives off sparks from its body while it is doing so. If its partner is in trouble, this POKeMON gives off increasing amounts of sparks.

Emerald
At a meeting of POKeMON academics, it was announced that simultaneous exposure to electricity from a PLUSLE and MINUN will promote circulation and boost vitality.

In the Video Games
In Pokemon Ruby, Minun can be found on Route 110. In Pokemon Sapphire, Plusle can be found on the same route, although it is rarer. In Pokemon Emerald, Minun is also seen at the same route with the same availability as Pokemon Ruby.

There are only two Trainers that use Minun in Pokémon Ruby and Sapphire. Both of these Trainers also have a Plusle. The first Trainer is a Pokefan, who is the first Trainer who you meet around the area where Minun can appear. This trainer sends out Plusle first, when it is defeated, it sends out Minun. The second Trainers is to the left, at the path which leads to the sea. There are actually two Trainers, but they are twins, so they fight together. The two Pokémon they use, are Plusle and Minun. They are harder to defeat than the previous Trainer, because there abilities make them tougher when fighting together. In Pokémon Emerald, where you meet the first Trainer, you see two trainers instead. When you walk past, both Trainers fight you, they both have a Plusle and they both have a Minun so they are harder to defeat.

In Pokemon XD:Gale of Darkness, you can find (but not catch) a minun (and a plusle) owned by the main charater's sister Jovi (in her room).

In the anime
Minun is rarely seen in the Pokémon anime without Plusle. Its first two appearances is the same Minun. It also appears with Plusle in the seventh movie and accompaning short. Its first appearance is in episode 314, where it, and Plusle, are attacked by Team Rocket.