Foes and Hero Races
Some foes may simply be other members of the sentient races of Hyrule, rather than a monster proper. For instance, the Heroes may have to fight their way into a castle, past some Hylian guards; they may have to deal with Gerudo pirates on their sailing ship; or they may have to deal with Deku guerilla fighters deep in the jungle.
Monsters can be assigned one (and only one) Race, for free, granting that foe the strengths and Vulnerability of that Race.