Here we have a No synergy run where Ashe tries to carry the two? In all sense of the run, indeed this was possible courtesy of Ashe unique buffs, where the team managed to cap damage due even with a Brother's summon.
The hardest part of this run is probably the first, where if you aren't careful and lucky, then most probably Firion will just move to hp attack you. So the technique here is break them 'before their turn' to prevent Firion from recovering from break with his brv regen buff.
2nd wave is pretty easy as they have simple commands and no noteworthy buffs. Just beware of turn order to not let them accidentally recover from break on their own turn.
3rd wave is the do or die. I did reset because of savage RNG but the trick is to not let Tidus get a turn at all and get Yuna's hp as low as possible when switching to Quistis support. Pop summon and proceed to kill Tidus and Yuna while spamming Blizzard with OK. Yes they resist it, but the 50% splash is worth it to close the damage gap. Then proceed to kill Jecht carefully after summon since Yuna is still probably be alive by then.
All in all this is a great challenge without a heal and with one character that can't reach his potential here.
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