As mentioned above, Poison is similar to the Water ability in many respects; Kirby can release spouts from his hat, slide around on a trail of poison, and throw poison blobs around. However, many of the Poison ability's attacks leave behind damaging residue (such as puddles or clouds) that can inflict continuous damage on enemies that touch them.
Kirby shoots a poison ball from his mouth that leaves a toxic puddle that can damage enemies. This attack falls straight down in water.
Up + B
Kirby projects a column of poison up in the air. Kirby can aim this attack in different directions (Tilted Toxic Tower).
Dash + B
Kirby surfs on a wave of poison. Kirby can surf on water while doing this attack. This attack also leaves a trail of poison behind it that can damage enemies.
Kirby breathes poison breath that damages foes. It can be moved by fans and can destroy bomb blocks.
B (near enemy)
Kirby goes into a flurry of poison jabs and then ends it by leaping into the air and slamming down. The slam produces a large splash of poison that can hit other targets.
Down + B (Midair)
Kirby fires two poison balls towards the ground, leaving damaging puddles when they hit the ground.
Dash + tap B (Midair)
Kirby throws a ball of poison which rolls around before bursting.
One concept drawing of Poison's ability hat depicts Kirby donning a purple wizard hat with a wooden staff. This might have been a nod to the character Garstein from Alcahest, an action RPG developed by HAL Laboratory. The relation between the Poison artwork and the character is that when Garstein joins the player, he talks about a cave being filled with poisonous gas.
The Poison ability can be obtained via several amiibos: Ganondorf, Callie, Marie, Inkling Boy (blue and purple), Inkling Girl (orange and green), and Inkling Squid (green and orange).