Unlike Pokemon, you don't need to catch the specific Pokemon on a specific location, instead you synthesize them. The synthesize rule is very simple: Two Lv 10 monsters. Lv 10 is very low level that even Lower Echelon Circle of Temper where the place you first unlock synthesis is enough for farming level.

Our journey first begin on Lower Echelon Circle of Temper where you unlock synthesis.

At this point, you can scout all families of monsters: Slime, Dragon, Nature, Beast, Material, Demon and Undead, so you can guarantee to synthesize all the families.

The only limitations are Metal Slime and egg exclusive monsters. You can get your first Metal Slime on Lower Echelon Circle of Caprice and first egg exclusive monsters on Middle Echelon Circle of Fortitude. Even so you can still synthesize most of the monsters (87.9%).

By the way don't forget to get Fizzy after you've gotten 300 monsters.

Even on Lower Echelon Circle of Temper, you can have a full team of final bosses to rule the whole world.

Still on the Lower Echelon and you can't still get egg exclusive monsters, but you unlock one more monster: Metal Slime.

Normally metal slimes start appear on Middle Echelon, but there is one thing that can work around: Mini Medal.

You can get one free metal slime with only 10 Mini Medal. You will get enough Mini Medal once you are progress to Lower Echelon Circle of Caprice (1 on Terrestria; 2 on Circle of Conquest; 3 on Circle of Temper; 3 on Circle of Indulgence; 1 on Circle of Caprice).

After that, you can get another one in Mole Hole.

After unlocking the medal slime route, the maximum monsters you can get will be 474 (90.6%). You can now focus only on egg monster on Middle Echelon.

Finally you unlock egg system once you first access to Middle Echelon.

In the PC version, you can find the egg location on the mini map so you don't need to rely on your bare eyes, though some eggs spawn may be season exclusive. The monsters in the eggs has fixed once you teleport to the map so you can't save load the result before opening the eggs. However you can save load before teleporting to the place you farm so you can regenerate another group of eggs.

Unfortunately you can only get white eggs and silver eggs on Middle Echelon meaning that you still can't unlock gold and rainbow egg exclusive monsters.

You can get almost all gold egg exclusive monsters once you first access to Upper Echelon.

Strangely, you can't get Hperanemon at this point which locking DQ5 final boss Nimzo and DQ8 final boss Rhapthrone.

You can only get Hyperanemon when you first access to Upper Echelon Circle of Caprice.

Unfortunately you still can't resurrect the Lord of the Underworld with Nimzo and Rhapthrone. We still need Psaro himself which is locked by that rainbow egg four arms lion.

You can only get Marquis De Leon after finishing the game. Rainbow egg is a little rare even on Upper Echelon Circle of Conquest, but I can still manage to get that with a few try.

Congratulation of completing the bestiary. You can now resurrect the Lord of the Underworld and turn the whole world into ash.

Lower Echelon Circle of Temper - Unlock synthesis - 460/523 (87.9%)

Lower Echelon Circle of Caprice - Unlock Metal Slime - 474/523 (90.6%)

Middle Echelon Circle of Fortitude - Unlock all white and silver egg exclusive monsters - 502/523 (95.9%)

Upper Echelon Circle of Temper - Unlock all gold egg exclusive monsters except Hyperanemon - 514/523 (98.2%)

Upper Echelon Circle of Caprice - Unlock Hyperanemon - 519/523 (99.2%)

Post Game - Unlock Marquis De Leon - 523/523 (100%)