The description of fall fall is:
Choose up to five creatures that fall within easy reach. A falling creature
the rate of descent slows to 60 feet per turn until the end of the spell. Yes
the creature lands before the end of the spell, it does not take damage from falling
and can land on his feet, and the spell ends for that creature.
This spell says nothing about a weight limit, so we can assume that there is none. If it's a creature and it's within 20 yards of you and you have the components (and nothing stops you from doing it), you can knock it down regardless of his weight.