Pikachu

Pikachu is an Electric typed Pokemon introduced in Generation I. Having appeared in four Super Smash Bros. games, Pikachu is tied with Jigglypuff for the most Smash Bros. game appearances as a playable character for the Pokemon universe.

It evolves from Pichu if the friendship is high (same as Riolu to Lucario) and can evolve to Raichu from a Thunder Stone.

Smash Bros.
Pikachu made four appearances in the Super Smash Bros. series as a playable character (Super Smash Bros., Super Smash Bros. Melee, Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS and Wii U).

In Smash Bros. Brawl, Pikachu got a final smash named Volt Tackle, which causes electricity due to it's Electric type.

Trivia

 * Pikachu was the Japanese mascot for the 2014 FIFA World Cup, but Japan crashed out in the group stage.