What boss/enemy did you have the hardest time with?

I nearly ripped my hair out and gave up forever fighting ruby weapon.

I maxed out all my characters gave them all the best armor, materia and weapons as well as their final limit breakers I also stocked up until I couldn't carry anymore potions or phoenix downs and I still died more times than I could count.

According to the game guide the boss becomes easier when there is only one person left alive... (which is kinda true)

Share your FF7 boss battle horror stories here!