Kirby (SSBU)/Down tilt
A crouching shin kick. Due to coming out on frame 4 with a hitbox that lasts for three frames and is interruptible at frame 21, it's one of the fastest down tilts. It launches horizontally and has a 30% chance of tripping opponents if hit with the foot and a 35% trip chance if hit at the tip of the foot, and this can happen even at high percents due to its very low knockback overall. Since it can trip opponents, it can set-up into stronger moves such as dash attack, forward smash, and even Inhale. If the opponent does not trip, it has some combo potential at high percents. As a result of Kirby crouching from the move, he can low profile moves such as Wii Fit Trainer’s Sun Salutation (all charges).
In addition to arguably being Kirby’s most effective neutral tool, it can also two-frame opponents at ledge. While it is safer than down smash, the latter is preferred due to its higher knockback and much better angling.