Bubbler

The Bubbler is a special weapon in Splatoon that temporarily protects the user from all damage.

Splatoon
For a short period of time, the Bubbler absorbs all attacks while making the user much more susceptible to knockback. A Bubbler can be extended to one's teammates by touching them, though all Bubblers spread in this way end at the same time as the original one. Its base duration is 4.5 seconds and can be extended with Special Duration Up.

Use

 * The Bubbler's duration is quite short and every moment must be used wisely. Splatting nearby enemies or moving through dangerous areas should be done quickly if the user is to take full advantage of it.
 * The Bubbler reaches its full potential when used cooperatively; shared among teammates, it can turn the tide of battle significantly.
 * The Bubbler is very useful in Splat Zones, allowing an entire team to make a powerful attack on (or a powerful defense of) a zone.
 * Like the Kraken, the Bubbler can be used in Tower Control to sit on the tower without taking damage. However, the increased knockback can make it difficult to stay on if enemies hit from the right angle.
 * It is important to keep in mind that a player using a Bubbler is still limited by their main and sub weapons: an Inkbrush Nouveau can still be outranged, a Custom Blaster can still be outmaneuvered, and so on.
 * A Bubbler that is about to expire will flash, signaling that the user will be unprotected very soon. If they are not paying attention to their remaining time, this can be taken advantage of for an easy splat.
 * Despite the invulnerability to weapons, players using a Bubbler can still be splatted by falling into water or out of bounds. The increased knockback makes this even more likely; pushing the Bubbler user into such pitfalls is a viable option, especially in stages like Moray Towers and Mahi-Mahi Resort.
 * Some Bubbler users may quickly activate it when engaged by an enemy, rather than as a strategic move. Caution must be used when dealing with these players. Though they may seem vulnerable in one moment, they can easily use their Bubbler to splat would-be attackers in the next.

Quotes
"You can never go wrong with Bubbler. When activated, a small impenetrable bubble appears around your character, rendering you invincible for approximately five seconds. Bubbler can also be shared with teammates. When activating Bubbler next to a teammate, they'll also get a protective bubble around them. You can also run into a teammate while Bubbler is active to give them Bubbler too - but it will only be active for the same remaining time as yours. So make an effort to seek out a teammate before activating this special. Due to its relatively limited duration, only activate Bubbler when you absolutely need it, such as the beginning of a firefight with an opponent. Bubbler is also effective when entering known high-traffic areas such as Splat Zones and chokepoints where you know enemy ink is flying."

- Prima Guide

Splatoon 2
In Splatoon 2, as explained in Sunken Scroll 11, no special weapons from the first game return. The role of the Bubbler was filled by the Ink Armor, as both form a temporary shield around the player that negates a certain amount of damage. The only direct difference involves sharing, as the Bubbler has to come in contact with teammates to share while the Ink Armor shares with all teammates simultaneously.

Trivia

 * The Bubbler was originally called the "Barrier", as seen in an image from before release.