The original NES cartridge allowed the creation of more unbalanced parties that aren't the same in the remakes.

Try:

Fighter
Fighter
Red Mage
BlackBelt

This combo is super-powerful with the benefit of some magic before and after class change. The BlackBelt can be solo-leveled until he is nigh invincible. And as always... the Fighters suck up all the damage and kill everything in sight as well.