The Bowser Bomb is a stall-then-fall move.
The move is based on Bowser's attack pattern in Super Mario Bros. 3 during his final boss battle, where he jumps diagonally forward and does a Ground Pound while facing the screen to attack Mario, breaking bricks below him. To beat him without power-ups, Mario has to make Bowser break all bricks on an area with the move, causing him to fall downwards into a pit.
Bowser Bomb returned as Mini Bowser's special ability in Mini Mario & Friends: amiibo Challenge.
If Bowser is on the ground when initiating the move, he will leap forward diagonally, pause briefly, then slam down to the ground with a high-power ground pound. When used in the air, Bowser remains airborne for a short time before landing down with the ground pound. Upon impact, the move produces small hitboxes in the form of shockwaves at both of Bowser's sides, which cause 8% damage in Super Smash Bros. Melee, and 11% damage in Super Smash Bros. Brawl and Super Smash Bros. 4. In Brawl and SSB4, an additional hitbox was added to Bowser during the diagonal jump when used on the ground, dealing 4% damage to anyone it connects with. The knockback from this hitbox can also combo into the ground pound itself.
In Brawl, Bowser does not get any freeze frames when he hits someone while falling, but the falling attack does have freeze frame properties in Super Smash Bros. 4.
When Bowser lands during the ground pound, he suffers significant ending lag, leaving him defenseless for a short period of time. However, he is still able to grab onto stage edges while falling as long as he is close enough to one, which eliminates the ending lag and also allows for an effective edge-guarding technique on opponents who are close to the edge while attempting to recover or hanging from the edge itself, as long as they are not affected by the initial intangibility frames.
In SSB4, Bowser Bomb deals drastically more shield damage, being able to shatter a full shield if all its hitboxes connect. However, this can be troublesome to perform, as the opponent may slide out of harm's way on the initial hitbox.
Bowser Bomb is shared by Giga Bowser, both in his boss appearance in Melee and in his playable appearance in Brawl and SSB4. Giga Bowser's variation of the move also features a glitch in Brawl. In Brawl and Super Smash Bros. 4, Giga Bowser's Bowser Bomb does not get any freeze frames.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
Edge-canceled Bowser Bomb
An edge-canceled Bowser Bomb happens when Bowser uses this move on an edge (while facing either direction). The animation and momentum of the Bowser Bomb is canceled out by the action of Bowser grabbing on to the ledge. This is useful when recovering from above. In Ultimate, the drop will meteor smash opponents, making for a useful edgeguard tool.
However, this requires precise positioning to successfully grab the edge. This positioning is made even more difficult by the fact that if Bowser is moving horizontally in the air before using Bowser Bomb, Bowser will continue to drift in that direction during the stall portion of the move.