The Pilots Gauntlet is a training simulation set on the planet Harmony. It's the 0th campaign mission and is split into two parts, the tutorial and the gauntlet.
Leading up to the events of the campaign, Captain Tai Lastimosa gives the protagonist Jack Cooper unofficial training sessions in this simulation. The simulated world was inspired by Lastimosa's home planet Harmony, but has some weird water physics.
The simulation is used to teach the basic movement and weapon skills in Titanfall 2 such as wallrunning, sliding, double jump, picking up weapons, aiming and shooting.
There is also a Nessie to be found on the first pillar to the left after leaving the corridor from the beginning.
The pilot tutorial ends in a gauntlet, where the player can test and improve his newly aquired skills. It features a leaderboard and a breakdown of your last run containing information like the highest and average speed or the amount of kills during the run. This gauntlet can also be started seperatly from the main menu.