Monsters all around the world map can be regrouped into species. A given species appears to possess common traits from one relative to another: behavior on map screen, proportions between stats, some combat skills, and lootable items.
Especially, it can be assumed that, within a species, the following items will be recurring possible steals/drops:
- Stat boosters
- Scrap Metal
- Alchemy Ingredients
- Equipment pieces
There are also "semi-recurring" steals/drops: the item will "increase" in level depending on the "importance" of the monster within a species (regarding order in the Bestiary and, if need be, Hard Mode...):
- Heal Potions (I -> II -> III -> IV)
- Mana Potions (I -> II -> III)
- Grenades (R -> S) ( -> Rocket, for some species)
- Gems (E/Am -> T/Aq) ( -> Ruby or Sapphire, for some species)
Note: the Bolt species is an utter exception to the rule, as each of the three relatives has its own set of characteristic traits...
Note 2: bosses are not included here, because of the divergence of their traits compared to the species they would be related to (different elemental sensibilities, skills, items,...).
(If anything is inaccurate/missing in any of the above assumptions, feel free to correct/add as you want)