In Final Fantasy IX I got stuck on Tiamat when I first played it. Back when it was the most recent final fantasy game and the PS2 hadn't been released. I finally beat it a year or two ago when I secured a copy and replayed through the entire game.
On a similar note I started Ocarina of Time shortly before the Gamecube and never made it past the forest temple as a kid. I later tried to complete the Master Quest version but didn't make it there either. Maybe three years ago now I used a friend's copy I was living with, but I had some difficulty (for the first time in that run) with Volvagia and never got back to it. So I still haven't beaten that.