hands down that the bosses with the constant lvls are the easier ones, unlike some others who match your level no matter how high it gets; in a way it makes sense to vary between both cases (some fights are easy if you've trained hard enough, but some are still tough no matter what) yet the ones with the constant lvls keep havin higher lvls as you get through each one so they get tougher too til teh end eventually
an i never was able to get 100 ultimas, but i always junctioned it to stat def; i had great other substitutes for strength (like triple.. i think). don't remember ultima's exact effect but it was HUGE, and affected all elements; so with a little flare and stuff you'd do great against elemental attacks
besides, str was never an issue to me cause i always had tactics either by magic (zombie->cure) status (playin wit stop, death, slow, etc..) or even regular stats with meltdown (on them) and mad rush (secret tip: berserk increases strength ;P); i even got some weaker tactics that involve (pain + haste) and so.. hehe m not an amateur anymorez