Guard class series

The Guard class series is the default class series for the Mars Adept Garet and his son, Tyrell. They are considered members of this class series if they either have no Djinn or only Mars Djinn set to themselves. This class series is unique to Garet in the GBA games; the other Mars Adept, Jenna, is a mage rather than a warrior and has her own default class set, the Flame User class series. The second Mars Adept in Golden Sun: Dark Dawn, Eoleo, also has his own default class series, the Pirate class series.

The class series, when at its highest stage of Hero and compared to the other series at their highest respective stages, features high HP, stronger Defense, and average Attack, but very low PP (shared only with the Slayer, Chaos Lord, and Acrobat and surpassing only the Beast Lord) and the single lowest Agility rating of all final-stage classes. This series' Luck rating is at the standard (which only the Squire class series and the two variations on Seer class series are also at). Noteworthy Psynergy from an endgame perspective includes Liquifier and Guard/Protect, and the heaviest area-of-effect Psynergy it has is Pyroclasm. Average stats from an endgame perspective are 135% (142% if you don't factor in Luck).

Psynergy Setup

 * Note: The Fire, Fireball, and Inferno Psynergies are replaced by Starburst, Nova, and Supernova in Golden Sun: Dark Dawn.

Analysis
Garet and Tyrell's Mono-elemental class is a tough customer, boasting above average HP and Defense, allowing them to take a bit of a beating, and the Guard Psynergy will allow them to ensure that their comrades can also withstand the punishment. The average attack stat will be boosted by their ability to wield Long Swords, while Inferno/Supernova, Heat Wave/Liquifier, and Pyroclasm will enable them to deal out some decent damage.

However, holding the single lowest agility stat will almost guarantee that they take their turn towards the bottom of the barrel, and their PP pool leaves something to be desired as Liquifier and Pyroclasm will quickly strain it.