King Dedede (SSBB)/Neutral attack/Hit 1
King Dedede swings his hammer forward. The move has long range, deals a rather high 6% and it has set knockback. The move's main hitboxes launch opponents horizontally which can be used to jab lock, making it a useable option after a missed tech.
However, the move is crippled by its slow speed. It does not come out until frame 12 and it has an FAF of 38, making it the slowest jab in the game. Its slow startup means that it cannot be used in pressure situations (especially since all of his tilts and grab are much faster and stronger), while it high ending lag makes it very punishable in any situation. In addition to this, it transitions very slowly into the second hit, which also has very high startup lag. Because it's knockback is not very high, this means that the move flat out does not combo into the second hit on any character at any percent. The move's main hitboxes are -4 to -6 on hit (depending on the opponent's weight) if Dedede performs the second hit, which allows some characters to hit him out of his jab or at least trade with the jab. The situation is even worse if Dedede does not perform the second jab, as the move becomes -12 to -14 on hit, making it even more dangerous for him to not perform the second jab, and giving the move no jab cancelling potential. The situation is even worse on shield, as the move only has two frames of shieldstun, leaving Dedede at -14 if he performs the second jab, or at -23 if he does not.
The move does have a sweetspot inside of Dedede which launches opponents vertically and has slightly higher knockback. This sweetspot is safer on hit and can make the move lead into the second hit more reliably, but it still isn't guaranteed and Dedede's opponent has to be right inside of him for the hitbox to connect, which is not a position he would want to be in when performing his jab.
When used as a jab lock, Dedede's jab is unfortunately unspectacular in this area as well. While it does have long range, allowing him to jab lock from long distances, and it does work at any percent on any character due to its set knockback and low hitting hitbox, the move's ending lag is so high that Dedede can only really chain a few jabs at the most. The move also does not lead into a guaranteed forward smash, so King Dedede has to use either a charged up/down smash or an up tilt after the jab lock for an effective finisher.
Because of these factors, King Dedede's jab is easily one of the worst in the game as while it has high damage and range, it is extremely slow, unreliable and unsafe to the point where it is punishable on hit, making it useless to use in most situations. Its only real use is as a jab lock but even then, the move is inferior to other jabs which can jab lock due to its slow speed. As a result, King Dedede's jab is extremely situational at best, and completely useless at worst, making it one of the worst jabs in the game.