Gear ability

Gear abilities, or simply abilities, are special attributes that are placed on wearable gear in and. They provide different effects depending on the ability present and their strength is based around the number of copies if they are stackable. Each piece of gear has a specific main ability which cannot be changed.

Secondary abilities
All gear has slots for secondary abilities (also called subs), which have weaker effects than stackable abilities. The effect is exactly three-tenths of a main ability. Certain abilities, due to how their effects work, such as Tenacity or Ninja Squid, are only present on a specific type of gear and cannot be rolled as subs. Secondary abilities are randomly chosen whenever a gear levels up, which happens when its bar is filled through battling; the points earned in the match go towards leveling it up. Higher rarity pieces of gear take more points and are longer to level up, even on the first secondary abilities. The amount of subs that can be present on a single piece of gear depends on the rarity (amount of stars) of the gear. The more stars there are, the more secondary abilities it comes with. Up to three secondary abilities can be present, meaning that the highest rarity is 3 stars. Many brands make getting specific abilities either more common or less common.

Subs are rolled using random number generation (RNG).

There are 14 rollable abilities in both Splatoon games. Brands that affect roll probability have a 5× chance of rolling a favored ability, and a 1/2× chance of rolling an unfavored ability. So, there is a 2/35 chance of rolling each of the 12 neutral abilities, a 1/35 chance of rolling the one unfavored ability, and a 10/35 chance of rolling the one favored ability. Brands that do not affect roll probability have a 1/14 chance of rolling each of the 14 abilities.

Stacking
Stacked abilities have diminishing returns, meaning that each additional ability of the same type will have a slightly smaller effect than the previous. Diminishing returns make it impossible for players to gain over-powered stats, and make it undesirable to stack too much of the same ability. All abilities in and  diminish at the same rate, but the effect may be more noticeable on some abilities than on others; abilities that have a small maximum effect or a small base stat being modified may feel especially ineffective to stack. For example, Swim Speed Up has a small maximum effect of 25%, so diminishing returns may seem severe relative to the other abilities. A player may not even perceive an improvement past a certain point, like after 3 main ability slots of Swim Speed Up.

This encourages players to wear a variety of different abilities, rather than focusing on one ability.

Mutual exclusivity
Some abilities can only be used in the main ability slot of certain types of gear, preventing the user from having more than one ability exclusive to that gear type. For instance, if a player equips Tenacity, they cannot also have Comeback because both abilities are only available in the main ability slot of headgear items. The groups of mutually exclusive abilities are as follows:
 * Headgear:
 * Clothing:
 * Because the has to be worn during Splatfest, only Ability Doubler can be used in Splatfest Battles.
 * Shoes:
 * Clothing:
 * Because the has to be worn during Splatfest, only Ability Doubler can be used in Splatfest Battles.
 * Shoes:
 * Because the has to be worn during Splatfest, only Ability Doubler can be used in Splatfest Battles.
 * Shoes:
 * Shoes:
 * Shoes:
 * Shoes:
 * Shoes:

Splatoon
Spyke, who can be found in an alleyway in Inkopolis Plaza, will offer to re-roll secondary abilities or increase the gear's slots in exchange for Super Sea Snails or 30,000 Cash.

In Splatoon, some abilities are ineffective with certain Sub Weapons and Special Weapons, offering no improvements.
 * Bomb Range Up has no effect on non-throwable Sub Weapons: the Ink Mine, the Seeker, the Splash Wall, and the Squid Beakon. It also provides no improvement for one throwable weapon, the Sprinkler.
 * Damage Up offers no further improvements after it causes a weapon to reach its damage cap.
 * Run Speed Up has no effect on the run speed while pushing a Roller.
 * Quick Respawn has no effect on respawn time after drowning or falling, unless the player uses more than four subs worth of the ability.

Mutual exclusivity
Some abilities can only be used in the main ability slot of certain types of gear, preventing the user from having more than one ability exclusive to that gear type. For instance, if a player equips Tenacity, they cannot also have Comeback because both abilities are only available in the main ability slot of headgear items. The groups of mutually exclusive abilities are as follows:
 * Headgear:
 * Clothing:
 * Shoes:
 * Clothing:
 * Shoes:
 * Clothing:
 * Shoes:
 * Shoes:
 * Shoes:
 * Shoes:
 * Shoes: