Pit is paralyzed by Zero Suit Samus' Paralyzer.
For the effect causing characters to be dazed for a period of time, see Stun.

There are a few attacks in the Smash Bros. series that cause the paralyze effect. Targets hit by these attacks will be frozen in place for about two seconds, shaking back and forth, before taking knockback. The user of the paralyzing effect can follow up with a smash attack or other powerful move during the stun, making the effect very useful. Repeatedly using a paralyzing attack will not increase the duration of the effect. This is often confused with the electric effect.

List of paralyzing attacks

By characters

Character Move(s) Games
Captain Falcon Lightning Falcon Kick (custom Falcon Kick; side hitboxes, landing)  
Dark Pit Dark Pit Staff (trapping hit)
Donkey Kong Focused Slap (custom Hand Slap; first of each pair)
Ganondorf Beast Ganon (trapping hit)   
Greninja Secret Ninja Attack (trapping hit)  
Ike Paralyzing Counter (custom Counter)
Kirby Ultra Sword (first trapping hit)
Link Triforce Slash (trapping hit)   
Little Mac Stunning Straight Lunge (custom Straight Lunge)  
Lucario Stunning Double Team (custom Double Team)
Pac-Man Bonus Fruit (bell)
Lazy Fruit (custom Bonus Fruit; bell)
Pikachu Thunder Wave (custom Thunder Jolt)
R.O.B. Super Diffusion Beam (second-last hit)
Robin Pair Up (Chrom's trapping dash)
Toon Link Triforce Slash (trapping hit)   
Sheik Light Arrow (trapping hit)
Paralyzing Needle (custom Needle Storm)  
Zelda Light Arrow (trapping hit)   
Zero Suit Samus Down smash
Paralyzer
Electromagnetic Net (custom Paralyzer)  

By items

Item Attack Games
Assist Trophies Starman: PK Beam γ and PK Beam Ω  
Poké Ball Pokémon Spewpa: Stun Spore

By enemies and bosses

Enemy/Boss Attack(s) Games
Devil Car Paralyzing fumes  
Kihunter Acid
Starman PK Beam γ and PK Beam Ω