Skull Bash

Skull Bash is Pikachu and Pichu's Smash B move in Super Smash Bros. Melee. It is similar to Luigi's Green Missile, only without the chance of a misfire and neither Pikachu or Pichu can hold the charge infinitely. The move can be charged up to increase the damage and range of the attack. Pichu can charge for longer, but hurts itself upon releasing (1%); the distance covered and the knockback when fully charged is tremendous, dealing almost 40% and nearly covering the length of Final Destination. It is used in most Home Run Contest strategies in lieu of the bat (fully-charged, Skull Bash is nearly a one-hit KO from Pichu). In Brawl, Skull Bash charges much faster than in Melee, and is an excellent move to recover with. When fully charged Pikachu will go about as far as the size of Final Destination. Though, unlike the Green Missile, you can't hold the charge, and when fully charged Pikachu will shoot forward. Even with it's great distance, it's not used too often as Pikachu falls at a quick speed. In Melee, Skull Bash has an electric effect when it hits, but not in Brawl.

Origin
Skull Bash is based on a move with the same name in the Pokémon video games. In the games, when a Pokémon uses Skull Bash, on the first turn it lowers its head, raising its defense, and on the second turn it launches at the foe. Strangely, Pikachu are no longer able to learn Skull Bash in the Pokémon games, while previously it could only learn it from a TM in Generation 1. When Melee came out, Generation 1 had ended, and yet Pikachu continues to possess Skull Bash in Super Smash Bros. Brawl, long after the end of Generation I.