Easy experience
To get easy experience for your lower level characters,
go into any battle and order your lower level character to attack
one of your own characters that has a much higher level. When
the attack meter appears, press [X] at the lowest point so
that the damage done is not too harmful. The amount of experience
gained depends on how large the difference is between the two
characters. The best place to do this trick is in the first set
of levels of the Tower Of Trial, where your opponents should not
be dangerous.
To level up coins to their Forbidden Force level, they must have
the following stats: MCP 160, RNG 7, AOE 25, POT 170. To reach
these stats, you must have coins that were either bought or found
at level 4. You can obtain a hidden level 4 Gain Coin in the Temple
of Earth battle with Blackthorn. Equip a party member with the
Hawkeye ability to find it. After you have acquired the specified
stats, engrave the emblem of the coin with another seal. For example,
engrave the Ema emblem and Tundra on your Gain Coin. Once leveled
up, they or their stats cannot be changed. When used, they will
hit everyone onscreen.