Hardest part

[Ayen]

The optional bosses were easily the hardest part in the game, good thing they were optional.

Agreed.

There weren't too many other tricky moments. I remember struggling to defeat Lost Number the first time I played.

The only mandatory bosses that ever gave me a hard time were the monster at Junon, the boss at Cosmos Canyon, and Sephiroth, and all three instances can be contributed to me not grinding.

Edit: I just realized I repeated myself here. My memory is getting worse.