How does the Luck stat work in Golden Sun?

Solution 1:

According to Golden Sun wikia:

Luck is the statistic that determines a character's chance of being inflicted by a status inflicting problem attached to an ability used against you, such as Sleep and Stun.

It does not increase your own chance of inflicting said status effects onto opponents, contrary to common belief. Having a luck rating of 40 or higher provides immunity to Poison, Venom, Haunt, Death Curse, the target's HP being instantly reduced to 1, and being forced out of battle.

So it does not have any effect on pickup, drops or critical hits, apparently.