It is completely possible to beat him with Mario at level 13, no cheats, no emulators, just whole lots of power gaming. It may be possible to do it with Mario at an even lower level, but I have yet to get there at a lower level than 13. Actually, I may have gotten there at level 12, but I can't remember right now. To do it you just have peach with the lazy shell and the magic scarf, let mario and <person> die whenever, and just heal up peach till culex runs out of FP. You have to have lots of FP recovery stuff, though, as he still one-hits everyone but peach with his regular attack.
Anyways, for hard bosses, anyone who said any boss from an RPG loses.
Any SNK boss gets my vote. The freaking term for hard bosses is that they have SNK syndrome, after all.
