they are hard.

Yeah, FFXIII's bosses are hard, though, I found chapter 11's final boss easy.

Need to find the right strategy cause if you don't beat him within a certain time he casts DOOM on the party leader which killed me off otherwise I woulda finished him on my first try...

They are a challenge, I'm grinding a bit before each boss. I think team is also important and ensuring you have the best role to stagger them.

I wouldn't call them hard, challenging is possibly better suited.

chapter 9 onwards their hp does shoot up, but you can overcome that easily by buffing your party, debuffing the boss and staggering. By the time you're near the end of chapter 13 you'll be able to deal over 4 million damage within a stagger depending on the monster/boss you're fighting.

I haven't found them too hard, the key is libra, and a defensive ploy. The only annoying thing is that they do take me much longer than the reccomended times, so my 0 stars is not satisfactory after such a hard gruel

That boss with 3.3m HP that the OP is talking about, it took me 22 minutes to beat, as I just had to stick with delta attack, with regular trips to combat clinic

...save your money fpr upgrading weapons...after you got to gran pulse, the difficulty will jump...
I spent so many hours at gran pulse trying to get money...it's hard to get gil in this ff....I did the chocobo treasure hunting soooo many hours.. lol

TBO i couldnt beat some bosses without wiki. Its a shame

ehh?
they were all pretty easy, only the last boss'es first form gave me some trouble, although I never upgraded my weapons while playing the main story (now I have some omega-weapons)