Tifa decides that she should get bigger first, and she has just the instument to do it with. With that realization, the materia reveals its powers to her. It happens to be called WG materia, it has 5 spells, WG1, WG2, WG3, Extreme hunger, and Create food. She could use these spells to her advantage, unfortunately only WG1 was ready, it was a small materia, probably the first ever. So now what would she do, her MP was low from the other uses, so she could only cast it a few times, but maybe she could use it in battle, give it enough AP to learn the other spells. Its worth a shot.