Wild Arms 3

1) Unlock the Secret Garden.
2) When you have a few Tiny Flowers to spare, start growing them and breed them up to be more stable in the environment. The rarer the items, the more it will need to grow. While the flower blooms as fast as the Heal Berries, it is the most resistant to the environment on Filgaia and starts at a horrible 5% blooming rate.
3) It takes one item redeemed within the Breeding option to increase the item's resistance potential by 1%, so for the sake of the Tiny Flower, it will need a whopping 95 Tiny Flowers in order to guarantee it.
4) Once you've acquired enough Tiny Flowers (probably 20 or less), go into your menu and use them on everyone to bring their luck to Best.

Now, a word of caution for the Gardening system. Items grow off of an in-game counter that you cannot see, but the values have been addressed. Talking to people or each in-game minute represents one point, fighting a battle rewards you with five points, resting at an inn gives you twenty points, and in-game cutscenes/events award you with one growth.

From there, the values of the items are thus:
Heal Berries, Tiny Flowers, and Revive Fruits require 25 points
Potion Berries, Holy Roots, and Mini Carrots require 50 points
Full Carrot and Mega Berry both require 100 points

Now, you could easily plant things, return to Baskar Colony, and just rest constantly to pass the time. Take anywhere from ten to thirty minutes of doing this, then return to the Secret Garden and claim your rewards. From here, focus on breeding up to rinse and repeat, and while this may be tedious, it would be the easiest way to max it out.

You can raise a single party member's luck through the luck guardian. With that said, this trophy requires all party members to be at the best luck. It's mostly random so while the luck guardian will assist for one party member, you just have to hope the other party members also get the best luck. Just keep playing naturally and this should pop eventually after a battle.