Bug Fables: The Everlasting Sapling

This is more of an additional note than a guide (although I'll give a couple of tips): If going for this achievement via the B.O.S.S rematches, you must defeat

I highly recommend bringing in a Queen's Dinner food item or two. You can get this via a chain of side quests involving helping cooks around the kingdom. Specifically the quests "I Wanna Get Better", "My Specialty" and "A Smiling Dish". It heals 15 HP, 15 TP, and fully cures the status of the entire party. For reference, when I did this, 2/3rds of my team had under the maximum total HP that the item provides. A couple of these, alongside a couple of safety Magic Seeds, and you should be good to go (this also applies if fighting the boss on Hard Mode during the story itself).

Here is the build I used. I was at rank 27, max rank, and had all rank ups invested in Medal Points. At that rank, my team had 86 MP and 15 TP. TP and HP will vary depending on side quest completion and how others choose to use the HP potions. Also, I had completed the quest to get the Chomper pet, which gave me an additional 1 damage per turn. Additionally, I had purchased the attack buff seed from the vendor in Defiant Root and gave it to Vi.

Vi (Front)

• Last Attack x2

• Power Exchange x2

• Antlion Jaws x2

• Poison Attacker x2

• Poison Defender x2

• Weak Stomach

• Eternal Venom

• Miracle Matter

Kabbu (Middle)

• HP Plus x4

• Super Block+

• HP Core x2

• Prayer x2

• Meditation x2

• Reflection x2

Leif (Back)

• Leaf Cloak

Team/Other

• TP Core x2

• Hard Mode

• Poison Needles

The idea with this build is to get Vi poisoned early to have high damage output while also never allowing her to take damage.

Turn order for "both" phases...

1st Turn
Assuming everyone is in the previously listed positions, press B to select Kabbu and use a food item on Vi to get her poisoned. This is best done with a Big Mistake (cook a mistake again to make a big mistake) as she will be poisoned and drop to 1 HP giving her another +4 to her attack from the 2 Poison Attacker medals and the 2 Last Attack medals (for those that don't know, poison will not drop a character below 1 HP.) Now attack with Vi using her Needle Pincer; with the attack buffs it should deal ~18 damage. Finally, use Leif's Bubble Shield Lite on Vi.

2nd Turn and beyond
Use Vi's base attack, which should deal ~10 damage, have Kabbu "Do Nothing," earning him 4 HP and 2 TP for the team, and use Leif's Bubble Shield Lite on Vi. If ever Leif gets low on health and TP is okay, feel free to use Kabbu's turn to heal them up. If they faint, use Kabbu's Pep Talk or a revive item such as Magic Seed to resuscitate them. If Vi goes down, have Kabbu continue to "Do Nothing," and have Leif use Bubble Shield Lite on themself; Miracle Matter will revive Vi after 2 turns with 4 HP.

Note - be sure to be stocked up with healing items. The Everlasting King has a nasty fire attack that hits the entire party. While insignificant for Vi and Kabbu, this can be annoying for Leif.