Captain Flynt is is one of the first Major Bosses in the game just after the minor bosses of Boom Bewm. He is faced at the end of the Best Minion Ever story mission.
One good strategy for this fight is to get a party together and designate one teammate to attack him from a distance while the rest deal with his minions. Getting too close to him will cause him to light you on fire. Weapons equipped with Fire Elemental power are not effective in this battle.