Pikachu

Pikachu is the mascot from the Pokémon series of video games. It is playable in every Super Smash Bros. title, where it has sometimes been associated with Samus, most notably in Super Smash Bros. Brawl.

Since Pokémon Diamond and Pearl Versions, Pikachu is given slight variations depending on its gender, with males having a whole tail, while females have a slightly notched tail resembling a heart. The Pikachu in the

Super Smash Bros.
In one of the artworks for Super Smash Bros., Pikachu was seen using headbutt on Samus, Donkey Kong, and Yoshi and launching them away. In addition, Pikachu's electrical attacks were instrumental in causing a glitch when used on Samus where her Power Suit is replaced with a silver polygon model.

Super Smash Bros. Brawl
In Super Smash Bros. Brawl, like the other fighters, Pikachu plays a role in Adventure Mode: The Subspace Emissary, and is paired with Zero Suit Samus (later Samus Aran when she regains her Power Suit) during parts of the journey.

Pikachu is first seen in The Research Facility (Part I), Zero Suit Samus discovers a Pikachu in a tank, being drained of electricity. She frees it and in return, Pikachu helps her regain her Power Suit.

Later on, they encounter Ridley who brutally smashes Samus against the wall until Pikachu uses Thunder on him. After they defeat Ridley, the pair eventually encounters Donkey Kong, Captain Falcon, Olimar, Diddy Kong and the Ancient Minister, who turns out to be a R.O.B. Knowing that the Isle of the Ancients is impossible to save from Subspace, all seven escape the isle in Captain Falcon's Falcon Flyer, though they are attacked by Meta Ridley on the way.

After they team up with the rest of the characters, Olimar's Hoctate Ship, Fox's Arwing, Captain Falcon's Falcon Flyer, Kirby's Dragoon, and Samus's Gunship can be seen flying into the portal to Subspace. The characters encounter Tabuu, who turn them all into trophies using his Off Waves attack.

However, King Dedede, Ness, and Luigi, the latter two having been given timed badges to revive them, collect each trophy. After the characters explore the Great Maze, Tabuu once again attempts to turn them into trophies, but Sonic destroys his wings, stopping him. After Tabuu is defeated in a final battle, Subspace is destroyed. Pikachu and the rest of the characters can then be seen overlooking a cliff, with a star in the sky to mark the Isle of the Ancients' former location.

Super Smash Bros. Ultimate
In the gameplay portion of the A Piercing Screech trailer for Super Smash Bros. Ultimate, Pikachu is dizzy and left vulnerable to Ridley on the Mario Galaxy stage, but a Metroid assist trophy latches onto Ridley long enough for Pikachu to recover and perform its side taunt.