So as a side project I've been working on a solo Noctis Coliseum team. I think I've got it down minus the Machine Killer Latents. Here's the team and why:
Noctis (RHades): Noctis is obvious, Hades inherit is better than my other gravity options because the extra time to combo should make Orpharion a bit easier to work with.
Dark Knight Cecil (Anaphon): Good stats, favorable board change (hearts help with stalling) Dark resist awakenings help with the nastier spawns and aid in stalling out the dark absorb on MHera. Anaphon inherit is almost 100% for stats. The board change and haste can be invaluable but it's no burst.
Dark Knight Cecil (Lumiel): as above, Lumiel is my solution to either the Tans or the Pys if I break the tans defense.
D/B Okuni (Orochi): High HP good attack and 2 TPAs to balance out damage, the finger and Skill boosts help in the opening to get actives up in case of emergency. Orochi is for things like Deightros, the puppets, and other nasty spawns.
Khepri (Nothing): She's the lynchpin to solving the Mech Zeus problem. And the Alnair problem, and pretty much any other combo shield problem. For Orpharion the plan is combo enough to drop it to almost 50%, pop Khepri, then RHades, then kill its ass dead.
Noctis (Facet): Facet should be obvious, kill the Machine God, then stall up and use it to kill Orpharion. Might be needed vs Deightros too but it's rarely been an issue.
Latents are 3 SDR and 1 machine killer on all but Khepri who gets 5 SDR. I'm presently lacking machine killers though to finish the job. Sheen would be a better burst (plus stats too) but my alt has Facet and the burst is still enough to get the job done where it needs to. If my alt pulls hades or sheen then I'll be swapping things around to make Sheen my burst (13 TE vs 10 TPA).