You can do whatever you want, as long as youre willing to adapt to a build and play it correctly, tactically as in - a part of a team. and that requires using environment and all items at your disposal.
You actually dont have to have all the skills in the team, but you also can - if you want.
I will not tell you how to play because i think discovering that for yourself is the most rewarding experience.
You can give Fire-Geo to Jahan, to Madora or to one of the two of yours.
Plus, you will be able to hire henchmen after a while so you will be able to take or create different kinds of support team members. And there is a kind of respec... (what a filthy word) later on in the game.
