My Views (note:the levels I am viewing these are from the normal level for them)
Igglanova:Easy enough, just don't screw up and end up having him use his physical attack
Igglanova 2: Easier, should only take 2 rounds.
Mile Sandworm:Fairly tough, just make be cautious
Juza:Not very hard, Force Flash is all you need to worry about
Zio:Impossible
Gy Laguiah:Strong physical attack, Fire breath is pretty weak though
Zio (actual):Not super hard, his physical attack is all you need to worry about.
Chaos Sorcerer:Joke fight! Flaeli might take 70 damage away from a single character though
Fract Ooze:Not to hard, and Techniques do a lot to him.
Dark Force:Fairly hard, just hope he doesn't use Bust Rocket alot.
D-Elm-Lars:Again, joke fight, might a little longer than Chaos Sorcerer, still easy though.
Xe-A-Thoul (X3):Pretty tricky, just try to be smart, and have healing planned
Lashiec:Fire Spells do a lot to him, don't worry about Possesion, Thunderhalberten is a little annoying to Wren, Another Gate is stronger.
Dark Force 2:Evil Eye works alot, Shadow Breath is brutal and Lightning Shower is a nightmare for Wren.
King Rappy:Not very hard, his Earthquake won't do much.
Dominators (X3):Easy, although it make take a few rounds.
Dark Force 3:Only 4 characters, Corrsion is annoying, Mindblast is annoying and Shadowbind is less threatning, his physical attack does alot though.
De-Vars:Not super hard, but lots of things only do 1 damage to him though (like Effes, Grandcross, Hewn(?) or Flaeli or Foi's or Zan's, not sure about Gra spells)
Sa-Lews:Again, not super hard, the more HP you take down, the more he will use Legeon and again sometimes might just do 1 damage to him
Alys: Super Easy, just use Crosscut on her, she will attack you, it might do about 50 damage, use it again she is defeated, and you get 1 exp point and meseta
Profound Darkness Form 1:Not super hard, Shadowbreath does a lot of damage, Firebreath will probably do only 1 damage to some, it might to more to people like Hahn or Raja.Don't really worry about Ray Breath.
Profound Darkness Form 2:Harder then the 1st one, it's physical attack will do a lot of damage, it has Lightning Storm which DF2 used, Another Gate which Lashiec used, and Distortion which is it's own.
Profound Darkness Form 3:The Final and Ultimate battle, it's physical attack is very powerful, it has Evil-Eye which will attempt to put a single character to sleep, Cancelling which Neutralizes your stats, and dun dun dun! It has Megid! Blasting the whole part for 100-200 damage, it is more damaging on Androids though, just keep healed and then you will win the fight for all Algo