In each of the seven different worlds there is a hidden flan that will challenge you with a minigame when you approach it. These different flavoured pudding monsters are collectively known as the Flantastic Seven and completing the mini games they challenge you with will enable you to recieve various items and even special abilities. These creatures will only spawn after having beaten the world where they live. So on the first playthrough they won't be there, they can only be encountered on replay.
If you manage to complete all seven of the minigames you will be rewarded with a rare material called Orichalcum which is needed to synthesize powerful accessories such as the Ultima Weapon. You will also be awarded with the Flanniversary Badge accessory which come with the ability MP Hastera. Below is a list of the minigames, the score you need to reach, and the rewards you can expect to get from them.
Cherry Flan Location
World: Olympus
High Score: 20,000
Rewards: Formchange Extender and Sour Cherry x 3
Banana Flan Location
World: Monstropolis
High Score: 20,000
Rewards: Grand Magic Extender and Banana x 3
Grape Flan Location
World: Arendelle
High Score: 20,000
Rewards: Unison Blizzard and Grape x 3
Honeydew Flan Location
World: San Fransokyo
High Score: 15,000
Rewards: Attraction Extender and Melon x 3
Orange Flan Location
World: Kingdom of Corona
High Score: 23,000
Rewards: Treasure Magnet and Orange x 3
Strawberry Flan Location
World: Toy Box
High Score: 17,000
Rewards: Attraction Extender and Strawberry x 3
Watermelon Flan Location
World: The Caribbean
High Score: 29,000
Rewards: Focus Syphon and Watermelon x 3
The video below will show you the locations and missions as well as an effective tactic to beat each of the Flantastic Seven.
#1 – Cherry Flan - 0:05
#2 – Strawberry Flan - 2:17
#3 - Blood Orange Flan - 4:20
#4 – Banana Flan - 7:09
#5 – Grape Flan - 8:47
#6 – Watermelon Flan - 11:00
#7 – Honeydew (Melon) Flan - 13:04