The inert effect is used by a small amount of attacks in the Super Smash Bros. series. Inert hitboxes are used for hit detection where a normal hitbox would be unsuitable, dealing no damage or knockback on their own. For example, the starting portion of Captain Falcon's Raptor Boost uses inert hitboxes to detect a target; contact with an enemy does no damage itself, but initiates the damage-dealing uppercut portion of the attack.

The inert effect was introduced in Melee, and it has appeared (though remained rare) in every game since.

List of attacks with inert hitboxes

 
Character Move Games
Captain Falcon Raptor Boost    
Heavy Raptor Boost  
Wind-up Raptor Boost
Dark Pit Electroshock Arm
Electrocut Arm
Quickshock Arm
Ganondorf Gerudo Dragon  
Ike Quick Draw   
Close Combat  
Unyielding Blade
Mii Brawler Onslaught
Mii Swordfighter Airborne Assault
Pit Upperdash Arm
Interception Arm
Quickdash Arm