Hmm...first playthrough battle would have to be X-ATM092. If you don't know he's there and don't save you have to go through Elvoret again. I should know; I ragequit when I was 8 because of that.
However I'd have to say the most challenging boss besides the weapons is the Mobile Type 8. Corona knocks you down to 1 HP then it follows up with Medigo Flare to kill you. Got to be quick there. I usually started with a Triple spell on someone at the start and triple-Curagad with high mag for like 6k hp.
However I'd have to say the most challenging boss besides the weapons is the Mobile Type 8. Corona knocks you down to 1 HP then it follows up with Medigo Flare to kill you. Got to be quick there. I usually started with a Triple spell on someone at the start and triple-Curagad with high mag for like 6k hp.