"FN-2187 was trained since birth to serve the First Order as a soldier and highly-trained marksman. A skirmish on Jakku awakened his conscience and drove him down a different path, one that earned him the nickname Finn--and established him as a leader of the Resistance."
Finn is a support hero for his team. Although more vulnerable in close quarters, Finn can hold his own, and he works best when he sticks close to his squad and team. As a "highly-trained marksman," Finn can more easily take out enemies in close to medium ranges with his Deadeye ability that automatically locks onto enemies while firing his blaster.
His team support abilities extend from here with his Big Deal ability. Upon activating this ability, a massive circular radius opens up around Finn, and everyone within the radius, including Finn himself, is granted bonus health, damage reduction, faster cooldowns for their blasters, and faster recharges for their used abilities. However this ability does does not allow Finn to sprint until it is deactivated.
Finn's final support-based ability is his Undercover Team. Best used for flanking and sneaking around enemy lines, Finn equips a GLIE-44 blaster pistol for close quarters combat and hides his fellow teammates from enemy radars while also revealing nearby enemies. Those within the circular radius also run faster.