Pikachu is tied for 29th on the tier list, alongside Blade, in the bottom tier. It has a decent movement speed, and better finishers than Blade. However that is pretty much where its strengths end.
Pikachu has only four moves at its disposal, the only one have so, half of them possessing flaws that make them near-unusable. its standard attack has extremely poor range, combined with a very long duration that leaves it wide open to attacks if he misses. Its Thunder is easily the worst projectile in the game, as it falls towards Pikachu, deals piddling damage, and has a long startup time that can be interrupted if Pikachu gets hit. These traits make it unsuitable for camping of any kind, as it leaves Pikachu wide open for a free punish. Because Thunder is also his down air, Pikachu has only one instant-KO attack, its up attack, while its other moves have little to no KO ability whatsoever. Pikachu has no way to deal with disjointed moves nor other projectile attacks.
These attributes give him awful matchups across the board (arguably worse than Blade), which is why it is ranked at the bottom of the tier list.
Pikachu uses Skull Bash, propelling itself forward a fixed distance, delivering a headbutt. This attack offers momentum canceling, aiding in Pikachu's survivability when launched off the stage, and it also aids in its horizontal recovery.
Pikachu uses Thunder where a large lightning bolt with infinite range spawns above Pikachu and travels from top to bottom, heavily launching opponents on contact. This makes it a better option for edgeguarding rather than as an offensive tool. There are still small differences between these attacks to note, though; one lies on the fact Pikachu becomes an actual hitbox if it initiates the attack in the air, which means Pikachu can deal damage by itself even before the lightning bolt comes down; this, of course, does not happen when it initiates it in the ground. Additionally, the grounded variant deals more damage per frame, as well as more knockback. Another difference is found on the fact the aerial variant can be held indefinitely by holding the attack button; in contrast, unless Pikachu is holding an item, he cannot held it while it is on the ground, performing its standard attack instead.
Because the differences between Pikachu's down attack and down aerial are so minimal and insignificant, coupled with the fact it lacks a jump attack, this makes Pikachu the only character in SSF to have less than the standard five attacks, with only four of them.
Blade and Pikachu are the only two non-clone characters to share a spot on the tier list.