A few of my characters have True forms which can only be fought or summoned after accomplishing special conditions.

True Ying: Defeat Ying MK2 three times to have him manifest himself as a deity of psychic energy.

Demoness Carol: Drain her demoness heart to its lowest level of charge for her to unleash its true potential.

Deity of the Damned: Kill Necronom to unleash her pent up necromancy powers, and unleash a monster.

Frukstev: Force Dai and Yuko to come to terms with their destiny.

Metal Omni: Complete his fortress gauntlet.

Other World Coal: Find him in silent hill and remain around him when the other world takes over.

The Perfect: Ascend the Clock tower and reach the top floor.

Nevermore: Simply find and attack him.

Daemon Prince Samuel: Stab Sam with a dark crystal and cause him to mutate to his true form.

True Aren: Weaken Aren till his demon form takes over.

Final Destination: Hurt Fate terribly physically, Emotionally, and Mentally.

Talon: Defeat Talon Company.

True Iso: Break Iso's Sword and unleash his locked away power.

Metal Perfection: Defeat or Summon Metal Omni, True Iso, Talon, True Aren, Final Destination, Nevermore, Daemon Prince Samuel, The Perfect, Other world Coal, Frukstev, Deity of the Damned, Demoness Carol, and True Ying.