How to unlock all Mentors (Dragon Ball Xenoverse 2)

There are a total of 25 Mentors located in Conton City in Dragon Ball Xenoverse 2, and by unlocking all of them you get four skills. They are scattered around the city, and in order to unlock them all you need to fulfill certain prerequisites. The Mentors are not found in the city until you have unlocked them, so start working on unlocking them before looking for them.

Each mentor will offer one Initiation Test followed by offering three more tests after. Completing all of these awards you with a special ability that the mentors used themselves. Defeating the tests also triggers the mentors to randomly help you out while questing and doing sidequests.

The following stuff is needed to unlock each Mentor, and the level requirement needed to start the Mentor training:

Krillin - Defeat Raditz + complete the first story mission.

Tien - Complete the first lesson given by Krillin.

Yamcha - Complete the first lesson given by Krillin.

Piccolo - Complete the first lesson given by Kuririn.

Raditz - Progress in the main story mission.

Gohan (Kid) - Progress in the main story mission.

Nappa - Progress in the main story mission.

Vegeta - Progress in the main story mission.

Zarbon - Complete the Frieza Saga.

Dodoria - Complete the Frieza Saga.

Captain Ginyu - Complete the Frieza Saga.

Friezer - Complete the Frieza Saga.

Android 18 - Complete the Future Saga.

Cell - Complete the Future Saga.

Lord Slug - Complete the Future Saga.

Majin Buu - Complete the Buu Saga.

Hercule - Complete the Buu Saga.

Gohan & Videl - Complete the Buu Saga and complete the side missions of Saiyaman.

Gotenks - Complete the Buu Saga.

Turles - Complete the Buu Saga.

Broly - Find Broly in the Buu Saga and reach the "God" rank on his mission.

Beerus - Complete the Buu Saga.

Pan - Finish all the story missions in the game.

Jaco - Finish all the story missions in the game.

Goku - Finish all the story missions in the game.