That's right. As long as you have the right materia for what you want to do, you can use them. All of our friends have different kinds, but we overlap sometimes with elemental spells. Most of mine are used for healing, protection and spells like fire, ice and lightning.

[there are in fact six or so slots on the staff that are meant to house her materia. she doesn't think to go into an explanation about the other magic she's able to do, but this will do for now.]