It is a visually modified version of the Tentatek Splattershot. It is an all-around weapon in terms of power, range, and rate of fire, making it easy to use for players of all levels of experience. It comes in a set with the Suction Bomb and Inkzooka. As the name implies, it is a replica of the weapon Octolings use.
The Octoshot Replica is obtained at the highest level out of any weapon in the game by far (40), with the other weapons capping out at level 20. This is because the Octoshot Replica is the only weapon to be given out as a Level Bonus.