The Pirate class series is the default class series available to the Mars Adept Eoleo. Eoleo becomes this class series when he either has only Mars Djinn set or no Djinn at all. This class series is unique to Eoleo; Tyrell, the other Mars Adept, has his own default class series, the Guard class series (shared with his father).
The class series, when at its highest stage of Hull Reaver and compared to the other series at their highest respective stages, has high HP and Attack, average Defense, and low PP and Agility, tying with the Admiral and Aqua Master. This series' luck rating is very high tying with . Noteworthy Psynergy from an endgame perspective includes Dragon Fume and Vicious Chop, and the heaviest area-of-effect Psynergy it has is Searing Beam. It is essentially the same as Jenna's Flame User class except it has no access to the Aura series. Instead, it has new Psynergy called Keelhaul which upgrades to Vicious Chop at the Pirate King class.
Eoleo's mono-elemental class's statistics are identical to the Aqua Squire, having high HP and Attack, average Defense, and low PP and Agility, but high Luck. The average defense is augmented by Eoleo's ability to wear armor, and the high attack stat is further boosted by his ability to wield axes. The Pirate has a good offensive Psynergy lineup, identical to Jenna's, but lacks the very useful Aura Psynergy series. However, sustained use of Psynergy is impractical, due to the poor PP pool. The Agility stat is nothing to brag about, since Eoleo will take his turn after many enemies. The high Luck stat is a bonus. Overall, the Pirate class series is a solid choice, but there do exist better options.