If you click "View rules" when looking at 100% category, you will find there is the definition:
Definition by XeroKynos: "Defeat all bosses, get all GFs, finish all side quests, have 1 of each item, have all cards (in possession), all characters have their ultimate weapon, all characters have learned all of their limit breaks, all junctionable GFs have learned all of their abilities (no abilities that can't be taught again were forgotten), all tutorial entries are known, enter all item shops and 12 Timber Maniacs magazines have been obtained."
This doesn't tell the whole story though, because "finish all side quests" is not exactly true. Easiest way to know exactly what you need to do, is to go through a run and see what is done, or at the very least read through the notes so you will see what we do.
Hey everyone!
We have decided to make a change to the ruleset for the PSX leaderboard. From today, the use of pre-manipulation will be banned and cannot be used in submissions. This is to finally bring PSX in line with the rest of the platforms, which had banned pre-manipulation.
We have spoken
