Tbh, most people probably ran very similar setups, just comes down to having the key units and a grid with a lot of vigor / exceed. F.e. think I ran:

Water (vs. Fire, Light, Water, Wind) with 2x Fenrir (1x Fen + 1x Hundo for off ele), Siegfried, Shiva, Lakshmi, Oceanus, Isis (sac), Atum (sac), Ea (BG acc)
Light (vs. Dark) with 2x Fluffy, Solomon + Sieg weapon, Take, Meta, Micha, Isis (sac), Atum (sac), Frey (BG acc)
Wind (vs. Thunder) with 1x Hundo, 1x Kyuki, Solomon + Sieg weapon, Isis (sac), Aza, Neph, Aether, Atum (sac), Arianrod

There are certainly slight variations on all teams that can potentially yield better results (+- 1m or so), but that's the general idea. Stun punishers, nuker, Echo bursts, as long as you can hit the 2m cap on everyone, get as much burst multi as possible.

My thunder's not quite there yet to compete with those scores and dark's unusable for this kind of stuff. Could've prob beaten my wind score with fire, but didn't wanna bother learning yet another strat. The score vs. thunder should've been at least a million higher, as my highest run was without Atum, but I'm an idiot who sold his Kyuki and since refreshing for a Kyuki helper takes approximately half an hour, at some point I gave up on having an optimal run.