The Rat in Parasite Eve II looks virtually identical to the rat in Parasite Eve, save for the mutations, to a standard rat. They are not nearly as dangerous as the first incarnation but can inflict POISON. They should be taken from a distance with any weapon (preferably with free or cheap ammo) or with an area of effect attack like Buckshot as using a spell would be a waste of a valuable MP.
Strangely enough, Rats have a 200% duration vulnerability to paralysis attacks. A Pepper Spray will last 40 seconds.