What I did involves a bit of spending on PSN. Get the DLC character pack that includes Plum (I can't remember which, DLC 3 I think?) and run her with Routier. This allows you to run an SP build with proper placement as soon as you hit 50 SP.
With my team of Seighart, Leonis, and Mimel, running that set allows you to do the EX Skill, Soul of Infinity. This can pretty much kill just about anything in one hit or 2 depending on the boss. I also use Alice for heals. It got me through the fights after Mimelia though it was all fairly easy for me up to that point. I mainly stuck with just who I was using and rarely swapped characters in the game.
Never really bothered grinding levels since levels don't seem to mean -your mother is a classy lady- in these games. Also, when you move from generation to generation, you can revisit the previous one and go to battle points to get components. A lot of the components come from equipment anyway.
Shishigami Bang Bang!