Hardest Bosses you have ever faced?

looking back, there was one boss in FF12 that was pretty hard to beat (for me at least) behind the door of Wrath was the boss known as "Chaos" which prevented you from attacking him. You would have to use magic or something to hurt him, i never really figured out how. But for someone who prided herself on powerful weapons and attack strength, it's pretty much the ultimate handicap. there were a few other hard bosses in that game as well like the hell wyrm

I don't recall who the final boss was in "M&L: Partner's in Time,"
but that reminds me of the extremely unfair Cackletta from Superstar Saga...
Seriously, bringing both bros' HP to 1 then unleashing an onslaught of attacks as the opening move?
Not cool.

After a couple tries though, I got pretty damn good at dodging all of her patterns. ^.^
(You pretty much HAVE to anyways.)

Fawful Express, mostly because the DS' microphone kinda sucks, so unless you know what the microphone needs, & can do it, you'll lose. Punching won't work, you have to use fire. Other hard bosses include: Super Peach's Castle, Durmite/Wisdurm, Mario Bros. vs Midbus, & Blizzard Midbus, if you don't know that hitting both the X & Y buttons makes you suck harder.

Gradius 3 Arcade Final Boss.