Just going to dump my rambled ideas here then:
Vigilante
www.d20pfsrd.com/classes/base-classes/vigilanteThe base class, see all rules here.
Vigilante - Magical Child
www.d20pfsrd.com/classes/base-classes/vigilante/archetypes/vigilante-archetypes---paizo-inc/magical-childThe class some (but maybe not all) of us may be picking. It includes "Transformation Sequence", summoner-level spellcasting, and a special familiar.
Vigilante - Cabalist
www.d20pfsrd.com/classes/base-classes/vigilante/archetypes/vigilante-archetypes---paizo-inc/cabalistMore likely to be an enemy than a PC. Uses witch spells. Yes, witch spells. Yes, that's what I said, witch spells. Yes, those.
Vigilante - Warlock
www.d20pfsrd.com/classes/base-classes/vigilante/archetypes/vigilante-archetypes---paizo-inc/warlockSummoner Spell List
www.d20pfsrd.com/magic/spell-lists-and-domains/spell-lists---summonerWitch Spell list
www.d20pfsrd.com/magic/spell-lists-and-domains/spell-list---witchOther classes:
Wizard:
Perhaps not all the characters are magical warriors who use dual identities and transform. They don't have a dual identity, perhaps because they come from somewhere far away, like another plane. Perhaps they are a mentor, a leader, a teacher, or a provider. Perhaps this person is the sole survivor of a terrible attack, enlisting heroes to aid them. Whoever this person is, they may not fit the other characters' themes 100%, but are important none-the-less.
Rogue:
The dashing hero who appears out of nowhere, saves the main hero or heroine in the nick of time when all hope seems lost, and gives the heroes a hint to win the battle. More likely to be an NPC played by the GM.
Interesting to note:
www.d20pfsrd.com/classes/core-classes/rogue/archetypes/paizo---rogue-archetypes/master-of-disguise-rogue-archetypeCleric:
Easily a spiritual adviser of the group, who runs a temple, church, or other holy place. This person assists the heroes often with advice, exorcisms, provision of items, and being an all around plot-advancement device. Also the person to bring wounded heroes to, and the one to send the heroes on a quest to get a rare herb to heal a wound they received from a deadly enemy as a way to provide more filler episodes. Also more likely to be an NPC.
Warlock:
Not quite fitting into the group, this person may be a rival, anti-villain, an anti-hero, or just someone working on their own. They have mysterious objectives and sometimes forge temporary alliances with the heroes.
Appearance
A magical child Vigilante doesn't use medium armor. This leaves armor like padded, leather, studded leather, and chain shirts. When we think of magical warriors, we tend to think of dresses, skirts, sailor uniforms, snappy suits, and other over the top uniform choices. Since battles are done with magic, these outfit choices rarely provide protection against swords and arrows and the like. When deciding what your character looks like when transformed, go nuts. Any color goes. Form can change. The transformation is magical and allows for creative thought. Want your studded leather to be a studded leather dress with frills and ribbons? Go for it. Afraid you cant get any cool factor with a chain shirt? Minimize the chain by using a lot of cloth or cotton with some chain meshing or lining. It's magical, it doesn't have to make sense!
Themes
Constellations: A popular group of magical girls name themselves after the names of the real world planets, drawing attack attributes from the gods the planets are named after. There are other heavenly bodies out there (hubba hubba) such as Dipper, Ursa, Orion, Cygnus, Gemini, Leo, Cassiopeia, Aquila, Auriga, the list goes on.
Names of Stars
Centuri, Altair, Vega, Castor, Pollux, Bellatrix, Aldebaran, etc
Names of Gods
Either original made gods, DnD 3.5 gods, or Pathfinder gods. A chosen warrior of each god?
Weapons
Sword, Spear, Rapier, Bow, each person can use a signature weapon!
Schools of Magic
Perhaps one magical warrior uses transmutation... another evocation, another abjuration, etc
Virtues and Sins
Good guy names: Justice, Virtue, Wisdom, Trust...
Bad guy names: Gluttony, Lust, Envy, Wrath, Pride...
Feelings and Traits
Despair, Determination, Tranquility, Ire, Creativity, Destruction...
Elementals
Earth, Fire, Wind, Water, Heart, BY YOUR POWERS COMBINED I AM CAPTAIN PLANET
Zodiac
Familiars and spells and names derived from the eastern zodiac
In game themes
A magical warrior each representing a country they are from in-game (encourages multi-racial!)