For the hell of it, I went through our godlike champs and mulled over how DF does against each of them..
Ones who beat him, with or without Masakados
Zophar (Fate storm overkills)
Lady (Calamity gaze + malice dirge D-combo overkills)
Jenna (Bhairava... kills. She has debilitate and all the kajas, so she can keep up with DF in a stat modifying war.)
Sephiroth (faster, shadow flare is a non-elemental 2HKO even through HP+60%)
Kuja (faster, flare star is a non-elemental 2HKO even through HP+60% thanks to how levels work in SMT:N. Death by forcibly being overleveled... shitty way to go.)
Albedo (faster, gravity gaze is a non-elemental 2HKO even through HP+60%, and I don't think gravity attacks fell under Expel until DDS - if I'm wrong then this match depends on what exactly you define expel as being. If holy Albedo still wins, if gravity/ID Albedo is screwed)
Yuna (go first, stall for time using protect, shell, autolife and healing until her OD gauge fills, then grand summon Anima who nukes the fuck out of DF with oblivion)
Emelious (DF's entire damage arsenal is provably evadable, including all the magic, so Shadow Wave spamming makes Emelious completely invulnerable in that fight. It takes Emelious hundreds of turns to kill since that move does pathetic damage and DF has all that HP and healing, but Emelious has a literal eternity to grind DF out.)
Heat (With tentacles; like Emelious he stalls forever and slowly whittles DF down)
9
Ones who he beats, with or without Masakados
Myria (strong physical + HP boosts reduces myria1 to a 4HKO out of the gate, rakukajas, makandas and tarundas interspersed with periodic healing reduce her to tinks, then poke her to death. For myria3, null death (which conveniently gets her paralysis too) instead of strong physical, since her relatively crappy damage doesn't require a resistor)
Fou-Lu (DF is a fair amount faster and isn't OHKOed and eventually stops being 2HKOed once he inflicts enough damage. Pierce ensures that he he can go through Fou's HP quick enough)
Ryu4 (nothing in his movepool can 2HKO an HP-maxed DF, and DF's healing lasts longer than Ryu's AP. Dekunda stops any Punk shenanigans)
Yuri (yuri1 needs to spam FtC to 2HKO, and his resources run out before a double. Yuri2 and DF could heal themselves and mana drain each other until the universe dies of heat death... except DF's going to eventually crit with one of his attacks and once that happens, gg)
Melfice (block silence, don't get 2HKOed. Melfice's doubles force a lot of healing at first but once DF can knock him down to a 4HKO with debuffs it's much smoother sailing.)
Orlandu (strong phys buys him 3 turns, focus friekugal for the gory kill)
Ash (strong phys (probably through Kamudo, I don't think Ash had status to exploit that), hurr around with magic until he crits. Toss in a few makakajas beforehand if needed)
Luca (void fire, bust Luca's attack so Luca's slashes don't 2 round, play the attrition game)
Empyrea (more strong physical fun)
Menardi (loooool)
9 (unless you count Menardi)
Ones where it matters whether or not you allow Masakados
Kefka (heal lock with fallen one, but Kefka can't actually do any damage through masakados until half his HP's gone, so DF has unlimted time to stack up stat modifiers and unleash one big attack. Without masakados he has enough variety to finish after a F1 no matter what magatama DF uses)
Ghaleon (DF needs to both prevent being solidly 2HKOed and prevent ID, and he can only do both with masakados since Ghaleon can do 120% PCHP with a physical + NE magic combo)
Piastol (2HKO with tempest dance or ID with eternum, only masakados can stop both)
Jade (2HKO with BoltX or ID with Rub, only masakados can stop both)
Ryu3 (he has a bunch of status and ID sprinkled throughout his list of transformations, something will work unless Masakados. With masakados, Ryu can still 2HKO with a high powered breath, but IIRC his dragons don't boost speed, so none of the dragons that can 2HKO will doubleturn before running out of AP)
Profound darkness (no masakados = 2HKO with one of the countless near OHKO moves in PD's arsenal. DF doubleturns sometimes but rarely, and given PD's HP he will run out of resources. With Masakados it depends on what you classify megid as (it is holy damage in game). Lump it under expel and PD doesn't do any damage, let it go through and PD wins as described above)
6
No idea due to no voting rights
Cloud of darkness
Eh, doesn't look so bluelike to me without masakados. That's 15 losses, and that's only champs.
Also if you lock his skillsets some of his wins would fall apart during a season due to not having the right moves
EDIT: Forgot that he can null physicals and elements with passive skills. That knocks out Kefka, Ghaleon, Piastol and Jade for sure, though he still needs masakados for PD and Ryu3 (their variety is just too great to cover with passive void skills alone).