Rainmaker

Rainmaker is a Ranked Battle mode in Splatoon that was announced in the Splatoon Direct on May 7, 2015 and will be added in a future update. In Rainmaker, teams compete for custody of the Rainmaker, the weapon shown above, which appears to be a metallic fish with a nozzle in its mouth, known in Japan as a Shachihoko.

Recently, it was leaked how this mode will work.

Rules
Rainmaker is a "Capture the Flag"-type mode where the teams must grab the Rainmaker, which is a golden fish-like item, and carry it to a goal at the enemy team's spawn within a time limit that activates once someone has picked it up. If the timer reaches zero, or the player holding it is killed, the Rainmaker will drop in place and regain its sheild.

The closer one team gets to the other teams goal, the team carrying the Rainmaker's goal will move closer to the center of the map, compensating for the increased distance the other team would have to travel otherwise. Only a single teammate can grab the Rainmaker, while the rest of the team will be tasked with defending them. The player holding the rainmaker cannot use Super Jump, but the Rainmaker itself can be used as a weapon, and acts similar to the Inkzooka special weapon. If time runs out before a winner has been declared, the game will automatically declare victory to the team who brought the Rainmaker closest to their goal.