This should help tremendously if your trying to beat the game

[MPG Annihilator]

I dont know why I didn't go into detail about it a few years ago, but I will do it now

A few tricks to help you get through the game easier

Tune and fuse up 6 Phoenixs. This will allow you to have lvl 50 Phoenixs, with High Healer and Cross Claw, making the game much easier to complete.
You can capture boss monsters. This makes getting the Mycalla, the best healer in the game, a lot less stress reducing. By tuning boss monsters, not only do you not have to capture them later, but you can find some really powerful monsters to add to your team.
Always get the killer move you need. There are slot B moves with killer on them, 4star, and do extreme damage to the monster it is strong against. This is literally the only good strategy to beat the game, and it is the most reliable for boss battles.
Tome of immovabillity. This allows you to fuse two monsters together and still get the same base, regardless of the monster that is not the base. Very useful to get high level monsters

[MPG Annihilator]

5. 6 note monsters shall never be used. Having one monster in your party significantly reduces your options and will kill you very fast.