For the characters in Dragon Ball Z: Kakarot, training is a lifelong commitment that they are more than happy to make. Warriors are more than willing to find ways to test themselves and push their limits. You can do this in the game by following the Turtle School training guide and completing the various tasks inside the manual.
To find the massive list of tasks available in the Turtle School Training Guide, you need to head to the main menu and then go to the history section. Click on it, but you won't find it in the big primary or secondary mission checklist. You have to tap on the left to view the manual. You can see how many tasks you have completed and how much remains to be done. However, these are not all tasks.
You must periodically visit Master Roshi on his island at Kame House. You want to come back with him regularly to complete missions and gain new pages for the training manual. These tasks vary from locating orbs of different colors, creating link bonuses in the community board, playing the game for a period of time, or increasing the level of a particular character. Unfortunately, you won't be able to grab any of these missions during the Namek Saga because you are on Namek, but when you return to Earth, be sure to speak to Master Roshi.
To get the Turtle School Legend achievement, you must complete 50 of these training challenges. The important point to remember is that you must speak to Master Roshi, or none of your training tasks completed and you will not be able to grasp any more.
