When inked, characters take extra damage from any source proportional to the ink's coverage amount, measured in its own units, which can be specified for each attack with the ink effect. This is visually manifested by the ink progressively covering a larger proportion of the affected character's model. The multiplier for damage taken by inked characters is determined by the formula
After a character is inked, the ink begins to deteriorate at a rate of 0.25 units per frame if the character is not hit by an inking attack for at least 120 frames (2 seconds). Therefore, ink takes 14 seconds to wear off with 60% coverage, and 22 seconds with full coverage. Similarly to the 1v1 multiplier, the additional damage applied to inked fighters will not affect the knockback any individual hit deals, or damage dealt to shields, but multi-hit attacks may KO earlier due to the fighter being at a higher percent when the final hit connects. Contrary to what is often believed, this is the only way for ink to deteriorate; button mashing, dealing or taking damage (even from attacks with a water effect), and swimming have no effect on the ink's duration. Alternatively, getting KO'd fully removes the ink.
Inkling's tank holds 150 units of ammunition, although these units are not to be confused with units of coverage. These units of ammunition are instead used for Ink Cost. For example, Inkling's neutral infinite will take 2 units of ink from the tank per hit, which will cover the opponent in 10 units of ink per hit. As a result of this, 18 hits of Inkling's neutral infinite will cover the opponent in 180 units of ink, thereby reaching the 1.5x damage multiplier cap.
The color of ink is entirely cosmetic, aside from potentially making the coverage amount harder to estimate. Only one color of ink will be shown at a time, with the color changing once the new color's amount of ink surpasses the old one's. The effects of different colored inks do not stack. An Inkling is also equally affected by having their own ink reflected at them, which can technically make it worse for the player should this occur. When Kirby copies an Inkling, he will use the first color of ink (in order of orange, blue, yellow, green, pink, cyan, light purple or dark purple) that isn't being used by an Inkling or another Kirby. Master Hand uses a light blue ink. Some Assist Trophies can also be covered in ink.
The stage can also be covered in ink, which reduces the moving speed and jump height of opponents while they are touching it. This is an additional property of a specific move, Splat Roller, rather than a side bonus of ink attacks themselves. The effect on jump height has unintended interactions with certain momentum-based moves, such as increasing their height.
Mr. Game & Watch's Oil Panic in Ultimate uses an effect similar to ink when hitting opponents, covering them in oil that deteriorates after a few seconds. However, this effect is completely aesthetic, and wears off much faster.
In addition to the above, attacks may have the ink effect, which produces specific graphics on hit. This is entirely independent of the ink mechanic.
List of ink attacks
In addition, all of Inkling's floor attacks have the ink effect, without applying the ink mechanic.
By enemies and bosses