Instructions
Move your party to any city on the map screen and select "Pub" from the city menu. Press the A button to enter the pub screen.
Select "Clan Trials" from the pub menu and then press the A button.
Select a clan trial to accept. Different clan trials will level up different clan talents. At the beginning of the game there are five clan trials available: "General Training I," "Adaptability I," "Aptitude I," "Teamwork I" and "Negotiation I." More clan trials are unlocked throughout the course of the game. Press the A button to accept the clan trial.
Press the B button twice to leave the pub and return to the map screen.
Move your party to the clan trial location. Review the clan trial location by pressing the X button to enter the menu screen, selecting "Clan Primer," selecting "Clan Trials" and then pressing the A button. A screen with the clan trial details appears. After moving your party to the clan trial location, the battle screen automatically appears.
Select the level of difficulty you want to play for the clan trial. Higher difficulty levels have harder objectives but will level up your clan talents more.
Complete the clan trial. Every clan trial and clan trial difficulty level has different objectives. A list of clan trials and their objectives can be found on GameFAQs. On trial completion, your clan talents will level up.