Luneth vs. Serge - Kneejerking that Serge can't deal with a physical blitz? Jump, attack again round 3 to finish the job. Serge only has Round 2 to play with here, and I don't think he has full healing or OHKO damage? (If Saints is a OHKO, then Serge likely wins.)
Luneth vs. Sasarai - EDIT: Status was faster than I thought. (Old post: Tentatively I think that Dragoon Luneth has a weird as hell heal-lock here? Luneth opens with jump, evading Pale Gate ID. S3 doesn't really have any killer buffs a la FFT Golem IIRC, so Sasarai does whatever (Earth Rune +20% Defense?!). Round 2, Sasarai defends, avoids the OHKO. Note that if the Earth Rune's wussy buff is good enough to allow Sasarai to survive, he probably just wins here, but I think Sas's HP is too bad for that to work. Round 3, Sasarai can heal really fast with Water Rune, so I don't think a Dragoon attack can finish the job, but apparently the closest thing to draining is the max spell on a Cyclone Rune? That's too slow. So Luneth avoids the issue and jumps again. Round 3 Sas heals, Round 4 Sas defends and Jump impacts... repeat until Sas has no healing left. Basically, jump is pretty badass when you're fast.)
Luneth vs. Marcello - Jump Marcello out. Marcello does his worst round 2, but on turn 4 he's eaten two jumps, and he doesn't have 2x PCHP durability.
Serge vs. Sasarai - Sas statuses Serge out somehow.
Serge vs. Marcello - Not huge Marcello respect?
Sasarai vs. Marcello - Probably 2HKOs first.