I would say the only FF I ever got 100% of what you could get was FFT. I had to develop my own Proposition guide to get all the Rare Treasure. Everyone had Zodiac, Ramza had Ultima, got the Genji set. I was real proud of myself...then the PSP version came out. I've heard that some items can only be gained through cooperative play.

That's almost as bad as the Chocobo World minigame to get some rare items for FFVIII (like Friendship). That aside I did get everything else for FFVIII so I consider it complete.

I found some mingames very challenging and could never work at it to get all the items (Flayer and Parasol for FFVII, lightning dodging and butterfly catching for FFX). Not having them never made much difference in beating the games of course.

Strictly speaking FFV and FFVI cannot be completed since you have several either/or choices: Chicken Knife/Brave Blade, Odin/Raiden magicite, get the sword or leave it as magicite. But you can get almost everything in a single playthrough.

I'm trying FFX-2 the second time through, but you need need three playthroughs to get at least one of everything, and I'm not sure I have the patience.

I got close with FFXII, but the final marks have left me discouraged. Not sure I'll ever get Lu Shang's Badge either.