[General Discussion] Overly Frustrating RPG Boss Battles - Sephiroth kicked my ass

I love a challenging boss battle in RPGs. In hindsight, getting frustrated with super powerful bosses was sort of exhilarating. xD Sadly, I haven't encountered many overly difficult bosses in recent games (PS2 era, specifically) but then again I just might not be playing the right games. Here are a few frustrating bosses I just thought of:

Final Fantasy III (NOT VI, III):

Spoiler:

The Dark Crystal Guardians. Damn, probably the most difficult FF-series bosses. I remember a couple of years ago when I finally got around to playing FFIII for the NES (after playing II...*shudder*) and I was blown away by these damn bosses. Echidna was a real bitch with her super spells and unfortunately very sound tactics. 2-Headed Dragon (whoa creativity right there) was a bit of a bastard; when I finally overcame his monstrous attacks and won I was pretty excited. ^.~ (<-- Arguably the most satisfying feeling in all of video games) Also, Ahriman, the last of 'em, was a huge pain in the ass. To this day, whenever I encounter one of Ahriman's brethren in more recent FF installments, I'm sure to kick it's bloody ass.

MegaMan Battle Network 3 (=.="):

Spoiler:

I like to think of myself as a master of the MegaMan Battle Network games. I know the battle system like I know how to breathe. Only one time ever have I been put in a spot of bother during a (boss) battle, and that was the final battle of MMBN 3. I think it's called ALPHA or something, and it caned my seemingly underwhelming chip folder. But thanks to some nice help from a GameFAQS boss guide, I beat him. (Ok, so I didn't really feel that happy; I hate having to stoop to guides for help on beating bosses...especially on the first run-through.)

Final Fantasy X (seems pretty popular in this thread, actually...):

Spoiler:

The funny thing about Yunalesca is that during my first playthough of Final Fantasy X, I defeated her on my first try. No help from guides, no nothin'. I think I just level-grinded pretty hard while I was at the Calm Lands. However every try since (I think 2 more playthroughs, like 4 years ago. Don't think I'll be returning to the game any time soon) I've struggled so much. She destroyed me so many times, it was ridiculous. Haha, and one time, I had obviously forgotten that the battle came in three parts...I defeated the first "stage" and I was like "*sigh* I'm so awesome *relief*" BUT THEN SHE TURNED INTO THIS STUPID OCTOPUS THING! (or was that the third stage? *shrugs*) My face was like =O, but I was so angry I killed her eventually. 8-)

There are a few more which come to mind, but those three will do. I would have loved to have put a couple of Suikoden bosses in there, but...there isn't a single boss in the Suikoden series that has given me troubles. Not a one. Oh well~ Although one time I struggled beating that rat in the Two Rivers sewer..=P (Suikoden II)

Oh yeah and if you "Threaten" Seymour Flux, he's powerless, FYI.

How ya doing, buddy?

Ozma. It's a killer. It's a rubber ball...

Spoiler:

...it's a killer rubber ball!

How ya doing, buddy?