Training Espers

From an esper's details screen, tap the Train button to go to the esper's training board.

After an esper gains SP from leveling up, you can spend them as you like on stat boosts or new abilities for the esper at the esper's training board.

The training board starts in the middle where the esper's icon lies. Tap one of the available panels to obtain the panel's boost or ability.
After you tap a panel, the panels next to it will become available.

If you evolve an esper, its training board will expand, and more panels will appear around the exterior.