Yuna

Yuna is a Light mage that can provide really strong heals, increase your survivability, and some good offensive skills that can deal high damage because of her high MAG. Her big downside is that she has negative physical attack resistances.

Aside from the lack of Esuna, she has what you'd want from a healer/support. Her main job helps increase survivability since it has Reraise, a pre-emptive revive skill that will last through the entire fight, and Curaga. SoS subjob gives Raise and Curada, essentially giving her more revives and heals if you need it. The Green Mage subjob helps increase your team's overall damage since it has Imperil, Deprotect, Deshell, and Vitalize, while Kotodama subjob is if you want her to be another damage dealer in your party.

Upgrading her to EX gives her one of the most important skills in her kit, and it's the Yevon's Blessing counter ability upgrade, becoming Aeon Bond. It makes it so that she can self heal when she's attacked (if the skill procs), which can end up full healing herself because of her increased healing power abilities. She can be quite a struggle to take down in PvP if you can't one-shot her, and if you can one-shot her, she will just revive if she casted Reraise on herself. Her EX upgrade also enhances Holy and gives Full Life, both are quite useful in general, making it very much worth it to fully upgrade Yuna to job lvl 25.

Since she's a Light element, she benefits from other Light element bonuses like Sakura's master ability, and the Bahamut vision card, both of which are considered to be top tier, ultimately making mono Light elements ahead of the others if you put them together. Recommended to pull if you happen to have them, or even Elsirelle instead of Sakura, but she's still a pretty good unit in general.

Max HP+10%・Light Attack+15 for all Light allies, own AoE Res+10