Pikachu is a playable character in the Brawl mod Project M. For its appearance in Project M, it was mostly reverted to its Melee version, while keeping a few techniques and moves from its Brawl and Smash 64 versions.
Pikachu ranks 23rd out of 41 on the official tier list, close to the bottom of B tier. This is a large drop from its placements in Melee and Brawl where it was 9th out of 26 and 8th out of 38, respectively.
Changes from Melee to PM
Pikachu was buffed in Project M overall, gaining many favorable attributes from Brawl while keeping others from Melee (such as its powerful up smash), along with a few other options being strengthened, giving it additional leverage against top-tiered characters.
Grabs and Throws
Up to date as of version 3.6.
In competitive play
Pikachu has received an additional costume where it wears its party hat costume from Melee and Smash 64, but purple instead of blue (It was blue before PM 3.5). It also received a special pirate hat costume, referencing a Japanese promotional card from the Pokémon Trading Card Game in which it appeared as Captain Pikachu (wearing the same hat). It also got an alt where it wears the (Brawl or post-Generation I version of) the Pokémon Trainer hat sideways and had its ears folded down.
Pikachu also gets costumes inspired by the 3DS game and live-action film Detective Pikachu, the equipment it wore in the anime episode Pokémon Emergency, Chase's hat from Pokémon: Let's Go, Pikachu! and Pokémon: Let's Go, Eevee!, May's headband from Pokémon OmegaRuby and AlphaSapphire, its green fedora from Melee, and its top hat and bowtie from the Pikachu's Jukebox segments of the anime. Other alternate costumes include the Harmony Scarf from Pokémon Super Mystery Dungeon, and a pair of headphones.
Z-Secret Costume: Pikachu Libre
R-Secret Costume: Pikachu with green backpack and bandana