Requirements for the 100% are as follows
1. Beat Sabuko, the final boss.
2. Destroy all the Sabu statues throughout the game. See the guide here
3. Beat the Secret Boss
.
4. Buy every food and equipment item from all the regular shops. Must not neccessarily be done with one and the same character.
5. Buy every special move for every character
Characters need to be at level 12 each to unlock all moves at the dojo.
6. Unlock at least one of each support characters. You don't need them in all color variations.
7.
MISSABLE! You have been at least on every screen of the game once!