Getting 100% in one play through is very possible, done it myself. However, there's something you have to do at the very beginning that is almost impossible to know about unless you have a guide. Also, the 100%-In-One-Game guide in the BradyGames guide is a little screwed up. Every online site that has a 100%-In-One-Game Guide (including this site) is just a carbon copy of it. There's only one that I've found that actually fixes those errors.

Anyway, the party that you are using is fine, but it won't be fine for every situation. Just use what the situation calls for, that's what the Garment Grids are there for. Although, when you get the Berserker Dress Sphere, go for the 4 countering abilities at the bottom first, it will make that dress sphere uber powerful.