first off, allosexuals face attraction based on the two biological sexes
the shit has nothing to do with gender, that pertains to feeling.
so bisexual refers to liking both SEXES, not both GENDERS
second, that's wrong too, the distinction was that bisexuals (as a term first used to describe sexual orientation in the 1950s) liked both sexes while pansexuals as a later term meant someone that was attracted to all genders. this is where pansexual becomes an inherently flawed term, since humans are generally not attracted to genders themselves but the body, which is defined by sex, itself
the only valid term to describe bisexuality is bisexual. "polysexual", "omnisexual", and "pansexual" are all wrong.