....Sorceress?!?!
hehehe, how she can use magic without junction? (limit break), only sorceresses have the innate ability of casting magic...or Selphie could be a monster from the moon! (monstres can also cast magic as innate skill)
maybe she is a sorceress but she never realized it, remember Edea, she can use exclusive spells like Ice Strike or Maelstrom, Selphie have 4 (...or 6, if you count Percent and Catastrophe) exclusive spells... i'm guess that is the only explanation for innate magic...
btw, that shouldn't apply to Quistis, since she only mimic the moster skills, i guess.