Both of them are pretty good, but have their weaknesses.

Gan is a very powerful mage able to spam spells, but not as skilled as a melee fighter. Her only sword training were impromptu fights with their Esteem while she was having lucid nightmares in Ishgard.
So she tends to approach fights with brute force and does everything to overwhelm the opponent, hit them before they hit you sort of deal. Casts spells and slashes with a sword simultaneously, but that requires a lot of concentration. If Gan runs out of steam, their stance will be way more shaky and you can easily defeat them. And they need to rest up and eat a lot after fights like these.

After having to fight Zenos so much and undergoing Garlean training Alma is an excellent melee fighter but not as good as a mage, able only to dish out very basic spells and preferring to enchant her weapons or fists instead.
Her main tactic is to outsmart her opponent and use many makeshift traps, mechanisms and basic spells in-battle to catch the enemy off-guard. Dirty tricks like using culinary tools or kicking someone in the crotch are included, Alma is Not Polite
However, she is not that good at dishing out constant damage without any creative or underhanded tricks. As soon as her gizmos run out she's kind of useless and will tend to fall back until she comes up with a new strategy. That's when she's the most vulnerable

I have a squad of idiots actually.
Besides Gan, Alma and Zol (all three are au ra), I have a Viera dude and a femroe!

Femroe is named Styredza, she's a daughter of a famous pirate who... was honestly too lazy to continue her dad's legacy and was kicked out by her own crew. After drowning her dad's ship with crew barely surviving, she's now aimlessly wandering Eorzea and looking for adventure gigs to pay bills. Despite being a lazy hot head she's a very talented arcanist and mathematician that knows some strategy, but is still too stubborn to apply herself properly

My Viera dude is a garlean ex performer, Elisey, whose troupe got disbanded after one of the Varis' propaganda laws. Elisey himself got dragged into military service. He hates it and half asses it most of the time. He had attempted deserting a few times and has a huge passion for writing and acting. From Stormblood to Endwalker he was working on a memoir

Gan is from my fan-made tribe of cryptids Magan! It's a tribe devoted to the study of black magic, so most of them are either black mages or dark knights. White magic is strictly forbidden (there's a reason for it aside from the obvious one). They left the Steppe a while ago and now mostly dwell in deep woods and mountains of any kinds, separate groups teleporting all over the world to trade with folks and exchange ancient evil artefacts, curses or wretched blessings for goods, services and political power. At worst they're truly terrible people following their khatun to a T, at best they're bitter tricksters. Perks of being a Magan include: taming voidsent, keeping them as pets and riding them instead of chocobos. Also playing ahriman piñata.