Final mage trial isn't too bad as long as you keep track of the boss HP (and I mean add up your damage to each one in a calculator) and make sure you kill both at the same time. Pixie has around 3K and the chimera has around 5K.

I had Sheli with 323 magic power, Alice with 260 and Masketta with 240. Sheli would alternate between Zelos lvl3 on the chimera and Lazelos to build up damage on both, Alice/Masketta were on madios/batilgref duty.
Once both of them are around 900HP from death drop a trio of La-spells to finish them off.

>>532540469
I did have Masketta in the back for one run but it makes it harder to heal your party and keep up the damage/debuffs if two of you get hit