Pikachu is currently 9th on the tier list because it is one of the better edge-guarders in the game, and on top of that it has good recovery and reliable finishers as well as a decent projectile. This results in Pikachu being an C tier. Having said that, it also has somewhat mediocre range in some non-electrical based attacks, and it is relatively easy to combo.
Pikachu is a small, light character with medium falling speed. It is also gifted with very quick speed and a very long and versatile recovery. Pikachu also has good upwards KO options including a fast, immensely powerful Up Smash (even more powerful than Fox's) and an Up Aerial that can semi-spike and KO characters at low percents. Pikachu also has a decent ground-hugging projectile (which means it can't be avoided by ducking) that can be used to setup approaches, but it still has limited approach. Pikachu has a few chain grabs that work on fast fallers, and its Down Throw is a reliable setup for a finishing move.
Pikachu's weakness lies in its range. Its grab and shield are the smallest in the game, and most of its attacks have low range. This hurts Pikachu in some areas, including approach and comboing, but in the end, pros should keep to the better side of its overall game.
Changes from Smash 64 to Melee
Given that Pikachu was considered to be the best character in Smash 64 due to being ranked 1st in the tier list, as well as having numerous advantages that made it so, when making to the transition to Melee, Pikachu was generally nerfed, similar to Ness and Kirby but its nerfs weren't as severe as theirs. Unlike the two, however, Pikachu still remains a viable competitive fighting force. Pikachu's overwhelming advantages from the previous game such as its huge range of its attacks that helps it to combo were weakened, but it was buffed in grab game and its attacks are more powerful, helping it to keep its ground at the 9th position on the tier list.
Pikachu received new voice samples that are higher pitched and more energetic.
Quick Attack travels slightly less distance, can no longer be extended by allowing the control stick to snap back to its neutral position, and has had most of its invincibility frames removed. This means it is also much less useful for escaping combos and maneuvering across platforms.
Thunder falls faster and a new glitch called ceiling glitch helps with edge-guarding.
Thunder no longer has infinite vertical range and now strikes at a fixed height from a thundercloud. It is also much slower and more laggy.
Pikachu rams its head at the opponent. The A button can be mashed rapidly for a quick series of headbutts.
Pikachu stands on its hands and attacks with both feet. This attack can be aimed up or down.
7% (tail), 6% (tip)
Pikachu whips its tail over its body.
Pikachu sweeps the ground with its tail.
Pikachu leaps forward and attacks the opponent with a headbutt. While this attack does have some knockback, it is rather laggy and leaves Pikachu vulnerable if shielded.
21% (early), 19% (clean), 18% (late)
Pikachu releases a jolt of electricity from its cheeks while leaning forward. The hitbox is disjointed, which makes it a wise choice for edge-guarding.
17%-19% (clean), 13% (mid), 7% (late)
Pikachu does a backflip and attacks with its tail. This is the strongest up smash in the game in terms of knockback and is extremely quick with decent range.
2% (hits 1-6), 3% (hit 7)
Pikachu spins around in place while surrounded in electricity.
12% (clean), 9% (late)
Pikachu performs a midair somersault, attacking with its tail.
2% (hits 1-4)
Pikachu spirals forward while emitting electricity from its cheeks. This attack hits multiple times.
12% (clean), 9% (late), 4% (landing)
Pikachu spins multiple times in reverse. This attack high lag, especially if Pikachu lands in the middle of the animation.
Pikachu flips and attacks upward with its tail. This attack is extremely quick with low knockback, which can be used to juggle opponents repeatedly. Also, if hit with the tip of the tail at certain points during the attack, the opponent will be launched at a nasty semi-spike angle.
12%, 4% (landing)
Pikachu spirals downward with electricity shooting out of its cheeks. This attack only hits once and can deal additional damage from the shockwave upon landing.
Pikachu zaps the opponent.
2% (hits 1-4), 2% (throw)
Pikachu places the opponent on its back and shocks them before launching them forward.
Pikachu does multiple backward somersaults before kicking the opponent away.
5% (hit 1), 5% (throw)
Pikachu throws the opponent upward and headbutts them into the air.
5% (hit 1), 5% (throw)
Pikachu places the opponent on the ground and jumps on top of them.
Floor attack (front)
Pikachu gets up and performs a headbutt on both sides.
Floor attack (back)
Pikachu does a sweepkick attack that hits on both sides.
Edge attack (fast)
Pikachu returns to the stage and kicks the opponent away.
Edge attack (slow)
Pikachu slowly gets on the stage and attacks the opponent with its tail.
Pikachu shoots a bouncing ball of electricity forward. The projectile travels forward while bouncing along the ground and can also travel up walls, below the edge, and along ceilings. If used in the air, Pikachu shoots the projectile at a downward angle. Disappears after around 3 seconds.
Pikachu moves at warp speed in two directions that can be directed with the control stick. The second warp is optional, but if used, the direction must be 45 degrees different than the first direction to work.
Waves at the camera, yelling "Pika Pikaaaaaa!" This taunt can be interrupted by any attack when Pikachu starts the second wave.
Note: According to the debug menu in Melee, Pikachu technically doesn't contain any idle poses. Instead, it will perform both its idle poses in one loop (mostly noticeable when Pikachu is currently holding an item). Both these animations become Pikachu's idle poses in future Smash Bros. installments.
In addition to the normal trophy about Pikachu as a character, there are two trophies about it as a fighter, unlocked by completing the Adventure and All-Star modes respectively with Pikachu on any difficulty.
It's safe to say that Pikachu is the most famous and popular of all Pokémon. It has electric pouches in both cheeks; when in danger, it shoots electricity at its enemies. Although Pikachu can evolve into Raichu by exposure to a Thunderstone, many trainers like Pikachu so much that they don't let it evolve.
Pokémon Red & Blue 9/98
While its electrical attacks, such as Thunder Jolt and Thunder, are powerful, Pikachu is at its best speeding around the fray and waiting for its chance to strike. You can control the path of Pikachu's two-directional Quick Attack, allowing you to jump twice. Hold down the B Button to charge up Skull Bash.
The angle of the Control Stick controls the direction of Pikachu's Quick Attack. Pikachu will move blindingly fast, and it will also cause damage to any character it runs into. Move the Control Stick during the Quick Attack and Pikachu will move in up to two directions. Be sure to check out the ceilings on the level when you use Thunder.
Pikachu can cancel its taunt into any attack or into its shield after the 60th frame (immediately after it starts its second wave). This can be used to trick opponents.
Thunder Jolt is not actually a move in the Pokémon game series, yet Pikachu uses it in the Super Smash Bros. series and at least once in the original anime. It is also an attack on some Pokémon trading cards.
This is the only game where Pikachu does not use an angry expression in any of its attacks.