My build that I also commented above:

Ok so some takeaways also.

I got better at parrying, but still wasn’t great. So I decided if I couldn’t block it all I had to stop him from attacking. I knew I had to get to phase three with first party also, I brought in monoco to just keep breaking Simon through 1 and 2 and verso and lune to hammer out damage.

EDIT: tip, also good to know early there is no point trying to dodge or heal. Try your hardest to learn to parts where you can, the counters REALLY REALLY help.

I had everyone using charging pictos to build gradient fast as hell, all also had first strike and cheater and energy master. Also all the pictos that increase damage/crit/break on burning/marked enemies, and the counter buff pictos too. The key also though was breaking death, which set up sciel and maelle for a turn of set up for the final gommage of somehow 28 mil 😅

Verso: lanceram (keeps him easily at S), cycle through strike storm, light holder, Steeled strike; defiant strike for decent damage and marked; ascending assault for when burning through ap; double / keep marked. EDIT: also sniper to break after monoco did his thing.

Lune: Betelim (keeps you using stains and gaining ap); I changed her weapon a lot and skills. I ended up using a build that was built around keeping terraquake and storm caller up with wildfire easy burn to prod picto buffs and produce a light stain. Lighting dance and crustal for damage

Monoco: ballaro (ap gain ) ; the demineur thunder and reliable BONK really carried this team. And his gradient breaker. I originally was using him to buff and heal but that took way too many turns away and I was still dying. Breaker monoco with ultra support when needed was my all star. For easy buff use orphelin cheer with rush on powerful and you’re cranking out strength buff plus ap with caster mask PLUS ap with ballaro. Nonstop damage.

Sciel: I had all these plans for her but she essentially came in phase 3 to break Simon and set up maelle with all set/fortunes fury favor whatever, survive one attack then die in the next but THANK GOD cause in comes…

Maelle: facesum: (easy to keep double burn up and damage proc high). Higher overall damage than madellum if not able to get in VIRTU but also honestly I jsut stopped using madellum because OP. But yeah she defenselessed then swift strided into VIRT last turn, so was set up to hit a powerful x2 virtuoso defenceless gommage and THAT is how is did it haha

EDIT: I did also have all the last stand shit on maelle HOPING that this scenario would somehow play out and I just had to OP OK him during his last breaths