Overview
In a nutshell
It is currently in the B Tier and holds 9th position, the lowest position of the B tier. This makes Pikachu closer to its original Top Tier status in Super Smash Bros, where it was ranked first place, as opposed to its D Tier status in Melee, where it is ranked twelfth place. It is currently the highest-ranked character in Brawl that has appeared in all three Super Smash Bros. games and the highest-ranked in the Pokémon series. Pikachu's decent KOing power, quick overall speed, good recovery and edge-guarding game, good chain grab (having two chain grabs), and Brawl's new physics have helped it a lot; Pikachu can no longer be so easily combo'd, its grab range is no longer the shortest (Ganondorf now has the shortest grab range), its Thunder is not as laggy, and it gained various new tactics such as Quick Attack cancelling. However, it has a relatively weak air game, placing it at a disadvantage against characters with particularly powerful air games, such as Olimar. Regardless, Pikachu still has very 
matchups, including an even matchup against Meta Knight.