PK Thunder

PK Thunder is a PSI attack which appears in every EarthBound game. It is also the up special move of both Ness and Lucas in all of their Super Smash Bros. series appearances, since Super Smash Bros. for the former and Super Smash Bros. Brawl for the latter.

When used, Ness and Lucas fire a ball of lightning that can be controlled using the control stick. When hitting an opponent, Ness's PK Thunder only hits one time before disappearing, while Lucas's is able to travel through opponents. Lucas's PK Thunder is also slower and has a shorter lightning "tail", but it can curve more quickly than Ness's.

Hitting Ness or Lucas themselves while the move is active causes them to fly forward. The direction they move depends on where they are hit. Like with the standard PK Thunder, Ness deals one hit with high knockback, while Lucas deals multiple hits.

In Super Smash Bros. for Nintendo 3DS / Wii U, Ness is given two custom variants for this move. The first is Lasting PK Thunder, which behaves like Lucas's version of the move, that it can pass through opponents and it controls more tightly, though it deals less damage. When it hits Ness, it propels Ness further than regular PK Thunder. The second is Rolling PK Thunder, which is larger, more powerful, and colored green, but does not move as quickly; hitting Ness also gives less distance, though it is also more powerful.

Trivia

 * In the MOTHER / EarthBound series, Ness and Lucas are unable to learn PK Thunder in their respective games; in Super Smash Bros. Melee the trophy for Paula, one of the characters in EarthBound who can learn PK Thunder, states that she taught Ness this and PK Fire, though no explanation is offered for Lucas. This explanation further returns as a random tip in Super Smash Bros. for Nintendo 3DS / Wii U.