I got the plat!
Ok, so my strategy for trial 100 worked out pretty well. Obviously you are going to want everyone high level, preferably 99, with all Espers (or Zodiark for sure). You also will want 3 ribbons, 2 nihopaulas, and some decent weapons like Wyrmblade and Zodiac Spear (you can steal these during the trials).
Have someone with Remedy Lore 3 and Nihopaloa use remedies on all the judges (equip a ribbon after hes done), The other two should have ribbons, Cast protectaga at the start of the battle, have your healer dispelga and curaja constantly, have someone (preferably a tank) use Enemy:any/Witther and have him go around withering all the judges.
Have your zodiark user summon, , immediately use his final eclipse spell, have him heal if he gets hit and run away from the judges, when the animation is over use an elixer on him and do it again. By this time Ghis should either be dead or close to it, finish her off, cast protectga again and repeat this process until only Gabaranth and Zargabath are standing. Have someone equip Nihopaula and use sleep cure items to put Zargabath to sleep on one side of the arena, then take Gabaranth to the other. At this point you want to make sure Gabaranth is wither'd to the point to where hes only hitting for a couple of hundred, every 10-15 seconds go use the sleep cure item on Zagarbath to make sure he doesnt wake up and elixer Gabaranth.
Once Gabaranth drops go finish off Zagarbath. The only hard part is surviving the initial onslaught, once you do that you should be good.
I'm really glad this remaster came out, when i played XII on the PS2 i didnt think much of it, but the remaster really changed my mind, its a great game. And my 8th Final Fantasy Platinum =D