Pikachu’s Jab is a headbutt.

Headbutt was a move introduced in Gen 1, but Pikachu couldn’t learn until Gen 2.

Pikachu’s Dash seems to be inspired by tackle.

Interestingly, despite the move being well known as one of the most basic Pokémon attacks, Pikachu has never been able to learn it.

Pikachu uses it’s tail for a few attacks.

This may derive from the move Slam, the description for which describes that a Pokémon can use their tail to perform the attack.

There isn’t much to be said for the Smash Attacks except for the Side Smash drawing special attention to Pikachu’s cheeks.

This is a reference to the multitude of Poékdex entries that state that Pikachu’s electric charges are stored in its rosy cheeks. While Pikachu’s cheeks light up for very electric attack in Smash Bros it’s made most obvious in the Side Smash.

Pikachu’s Back Throw seems to reference submission, the strongest Gen 1 fighting type move that the Pikachu family could learn.

In Japanese, this move is known as “Hell Wheel” and if your familiar with fighting games this should sound familiar. Even Ken’s Back Throw in Smash Ultimate is named the Hell Wheel!