Fira vanguard, Ryu Lia Nia rear

The battlefield would be a forest. Open but full of obstacles, a sea of trees where both they and their enemies could freely move around in all directions, but with limited vision of their surroundings.
No, the baboons lived here so it was wise to consider their view wouldn't be as obstructed as theirs, just like the trees may actually be of help to them rather than hindrances.

How to counter that?

Ryu was great in defence, but both his attack range and power were lacking.

Fira instead had great attack power and thanks to her halberd, range was her forte. Defence, on the other hand...

Lia was good in all kind of elemental spells, but her support skills were lacking.

Niah'la got good healing and support moves, but her actual fighting capabilities were somewhat lacking when compared to the rest of the group.

How to position the troupe to make the best out the field and their abilities?

After some discussion it was decided that Fira would take the lead and walk ahead, whereas Ryu would follow behind the other two.
This way Fira would be able to make the best of her attack range by razing down any enemy on their way while assisted by Lia's magic, whereas Ryu would protect the rear from sneak attacks toward the two casters.

Lia magic would be wind based against single enemies whereas ice would be used against groups should a big number come up against them. After all, using fire magic in a forest was just asking to be branded as an arsonist.