A quick overview of maps, bestiary, medals, bonus skills, minigame locations and sidequest locations to help you finish off everything the game has to offer.
All information belongs to ayumilove on their wordpress site. I dont own any of this.
All information originally found here https://ayumilove.wordpress.com/2010/09/04/epic-battle-fantasy-3-walkthrough/ .

You need the Old Key to get the chests in the South East Town.

There is a unmarked 9th chest on Rock Lake (6). It is left of M1.

01. Green Slime : Forest
02. Giant Green Slime: Forest
03. Blue Slime: Beach, Glacier Valley
04. Giant Blue Slime: Beach medal area, Glacier Valley
05. Red Slime: Volcano
06. Giant Red Slime: Volcano
07. Yellow Slime: Beach medal area, Kitty Ruins, Volcano
08. Furry Slime: Forest
09. Blue Jelly: Beach
10. Purple Jelly: Beach
11. Red Jelly: Beach
12. Garden Snail: Forest
13. Spiral Crab: Beach
14. Spike Crab: Beach
15. Green Bush: Forest, Forest medal area
16. Red Bush: Forest, Forest medal room, Volcano, Volcano medal room
17. Dark Bush: Volcano, Volcano medal room
18. White Bush: Forest medal room, Glacier Valley
19. Leaf Eater: Forest, Kitty Ruins, Kitty Ruins medal room
20. Glacier Eater: Glacier Valley, Kitty Ruins medal room
21. Lava Eater: Volcano, Kitty Ruins medal room
22. Rock Eater: Volcano
23. Swift Crow: Forest, Volcano
24. Mage Bird: Beach, Kitty Ruins
25. Thunderbird: Kitty Ruins
26. Haunted Tree: Forest, Beach
27. Yellow Bee: Forest, Beach, Kitty Ruins
28. Purple Bee: Forest, Beach, Kitty Ruins, Volcano,
29. Red Bee: Beach, Kitty Ruins
30. Dark Moth: Volcano
31. Kitten Soldier: Forest, Beach
32. Kitten Fort: Beach
33. Trojan Horse: Forest, Beach
34. Shark Igloo: Glacier Valley
35. Eyeball: Beach
36. Beholder: Volcano
37. Red Clay: Beach, Kitty Ruins
38. Blue Clay: Beach, Kitty Ruins
39. Light Clay: Kitty Ruins, Kitty Ruins medal room
40. Dark Clay: Kitty Ruins, Kitty Ruins medal room
41. Frozen Eye: Beach medal room, Glacier Valley
42. Holy Eye: Glacier Valley, Kitty Ruins
43. Ancient Eye: Kitty Ruins
44. Gunslinger: Kitty Ruins
45. Swordslinger: Kitty Ruins
46. Ice Bit: Glacier Valley, Kitty Ruins medal room
47. Fire Bit: Kitty Ruins medal room, Volcano
48. Ice Elemental: Glacier Valley
49. Earth Elemental: Forest medal room, Kitty Ruins
50. Fire Elemental: Volcano
51. Light Golem: Kitty Ruins, Kitty Ruins medal room, Volcano, Volcano medal room
52: Dark Golem: Volcano, Volcano medal room
53. Sandworm: Kitty Ruins, Kitty Ruins medal area
54. Drill Bot: Volcano
55. Skull Ghost: Volcano
56. Viking Monolith: Glacier Valley, Kitty Ruins medal room, Volcano medal room
57. Ancient Monolith: Kitty Ruins, Kitty Ruins medal room, Volcano, Volcano medal room
58. Cosmic Monolith: Volcano, The Void, Volcano medal room
59. Zombie Dragon: The Void
60. Jack(Boss): Forest
61. Giant Squid(Boss): Beach
62. Squid Arm: Beach
63. Tundra Mammoth(Boss): Glacier Valley
64: Protector(Boss): Kitty Ruins
65. Rock Rune: Kitty Ruins
66. Fire Rune: Kitty Ruins
67. Bolt Rune: Kitty Ruins
68. Holy Rune: Kitty Ruins
69. Abyss(Boss): Volcano
70. Blaze(Boss): Volcano
71. Czars(Boss): Volcano
72. Rune Claw: The Void
73. Evil Worm: The Void, Volcano medal room
74. Evil Tail: The Void, Volcano medal room
75. Akron(Boss): The Void

Savior: Defeat final boss
Hero: Beat game on Hard or Epic
Legend: Beat game on Epic
Equip Fan: Get 40 pieces of equipment
Equip Dealer: Get 60 pieces of equipment
Equip Master: Get 80 pieces of equipment
Shopper: Buy everything in the equipment shop
Squire: Defeat the Robot Pumpkin
Swordsman: Defeat the Giant Squid
Warrior: Defeat the Wooly Mammoth
Knight: Defeat Protector
Lord: Defeat the 3-Headed Pyrohydra
Brute: Deal 1k damage
Ruffian: Deal 3k damage
Savage: Deal 10k damage
Barbarian: Deal 30k damage
Slayer: Deal 100k damage
Level Builder: Level 10
Power Leveler: Level 20
Level Grinder: Level 30
Helper: 10 sidequests
Tasker: 20 sidequests
Quester: All sidequests
Treasure Hunter: All Town chests
Forest Treasure: All Vegetable Forest chests
Pirate Treasure: All Rock Lake chests
Frozen Treasure: All Glacier Valley chests
Ancient Treasure: All Kitten Ruins chests
Burnt Treasure: All Volcano Peak chests
Beast Tamer: Scan 25 foes
Beast Hunter: Scan 50 foes
Beast Scholar: Scan all foes
Hoarder: 10k gold
Banker: 50k gold
Nouveau Riche: 250k gold
Greedy Cat: 100 points first minigame
Fat Cat: 140 first minigame
Narwhal Rider: 100 second minigame
Narwhal Surfer: 150 second minigame
Card Flipper: Under 90 third minigame
Card Wizard: Under 65 third minigame
Skeleton proof: 160 points fourth minigame
Skeleton Killer: 230 points fourth minigame
Rock Dodger: 130 points fifth minigame
Untouchable: 190 points fifth minigame
Fatty: Eat a hamburger
Slime Splatter: Splat 100 slimes in the preloader
Berserker: Use Bersek in battle
Doomsday: Cast Doomsday in battle by using a dark rune
Nuke: Use Nuke in battle.
Genesis: Use Genesis in battle
Ragnarok: Use Ragnarok in battle
Learner: Learn a new skill
Blacksmith: Fully upgrade any weapon
Pervert: Click Nat’s bosom
Cat Tamer: Summon Meow Meow (Use Meow Meow Skill)
Narwhal Tamer: Wear Pirate Gear level 5, get hit with it on, randomly summons Narwhal
Pig Molestor: Hold down spacebar behind a pig (click a pig a bunch)
Artist: Unlock the full concept art gallery, see the final page
Creditor: Check the credits page

Berserk (Max L2)
Option: Matt/Natalie (Recommends: Natalie)
Obtain from: Heinkel (Vegetable Forest 8) //Old Man
If targeted on an ally, you will lose control of them.
However, it will improve the character's physical attack and defense!
Applicable on foes too. The berserk will use basic attack.

Dispel (Max L3)
Option: Natalie / Matt (Recommends: Natalie)
Obtain from: Rock Lake Secret Area (20 Medals to enter)
Cancels all enemy buffs. Great asset in boss fights and monolith battles.

Flare (Max L3)
Option: Natalie / Lance (Recommends: Lance)
Learned from the guy at the cave near the lake.
Decreases enemy accuracy.

Meow Meow (Max L3)
Option: Natalie / Lance / Matt (Recommends: Natalie)
Obtain from: Meow Meow (Vegetable Forest Town, nearby Inn)
If given to Natalie, it will be her only physical attack.
Damage does not depend on stats but level.

Power Metal (Max L5)
Option: Matt / Lance (Recommends: Lance)
Obtain from: Johnny (Vegetable Forest Town Center) //Rocker
Magic that hits all foes and heals all party members.
Element: 100% Wind

Syphon (Max L3)
Option: Natalie / Lance (Recommends: Lance)
Obtain from: Vegetable Forest Secret Area (10 medals to enter)
Prevents enemies from using magical skills such as Magebird.

Tera Drill (Max L3)
Option: Lance / Matt (Recommends: Lance)
Obtain from: Simon (Kitten Kingdom Ruins 7) //a guy with a drill
Deals massive damage to foes that have buffed up defenses.
Use this before casting Dispel. Deals 25% Earth Element damage.
Best not to use on monsters that have earth as a strength.

Guardian (Max L5)
Option: Matt/Lance/Natalie (Recommends: Lance)
Obtain from: Celeste (Glacier Valley 4) // a girl with Pope dress
Buff an ally defense, magic defense and evade.

Mini Game: Food Catcher (Vegetable Forest 9 – Sir Ken)
Mini Game: Narwhal Surfer (Rock Lake 7 – James)
Mini Game: Cards in the Snow (Glacier Valley 8 – Joanne)
(Take a screenshot of the CITS picture to easily beat it)
Mini Game: Ruin Raider (Kitten Kingdom Ruin 8 – Dishi)
Mini Game: Rock Runner (Volcano 9 – Curly)

NPC Quest Location (1st Row)
Rusty – Vegetable Forest Town (South West) *Nearby Misc Shop*
Konata – Vegetable Forest Town (Center)
Johnny – Vegetable Forest Town (Center)
Calum – Vegetable Forest Town (Center)
Meow Meow – Vegetable Forest Town (East) *Nearby Food Shop*
Mattie – Vegetable Forest Town (South West) *Nearby cows*
Ronald – Vegetable Forest Town (South East) *Nearby Grave*
Carl – Vegetable Forest Town (East) *Inside the Inn*
Jim – Vegetable Forest Town (Center)
Jenny – Vegetable Forest 3 *Nearby Vegetable Forest Secret Area*

NPC Quest Location (2nd Row)
Yui – Vegetable Forest 3 *Nearby Vegetable Forest Secret Area*
Heinkel – Vegetable Forest 8 *Just before the Pumpkin Boss Map*
Ralph – Rock Lake 1 *Partly hidden on the left side*
Kimberly – Rock Lake 2 *She is naked (partly censored)*
Joseph – Rock Lake 3
Bartolo – Rock Lake 5
Krystal – Rock Lake 9 *Nearby the Warp Zone*
Alana – Glacier Valley 1 *Talk to the person twice to get quest*
Blondie – Glacier Valley 1
Vicky – Glacier Valley 2

NPC Quest Location (3rd Row)
Celeste – Glacier Valley 4
Hajime – Glacier Valley 4
Simon – Kitten Kingdom Ruins 7
Yoko – Kitten Kingdom Ruins 7
Ginger – Kitten Kingdom Ruins 8
Targold – Volcano 1 *Beside the red camp*
Eldoran – Volcano 1 *Nearby the red camp*
Sally – Volcano 3 *Nearby the giant door room with 4 pillars*
Souru – Volcano 1 *Between Targold and Eldoran*