Lilka is also a similar type that popped into mind where they might not be dead weight. Also, Justin, oddly enough! Probably good that I think his fight got cycled out, because his ST Elemental Attack+MT Combo would be unpretty for the P3 characters. It really does depend on what they face though, so it could be possibly that between the normal two choices there might be enough leeway to make the P3 characters face their weaknesses rarely enough for it to matter (Good thing Yukari/Aigis are mostly deadweight floor 1 anyways, I think!). Although, just looking over the last 5 weeks or so...
Floor 2: L'Arachel, Magus, Halley, Keith, A few VP fighters who can hit elemental weaknesses (Just not 100% sure what they are off the top of my head!)
Floor 3: Flik, Deis, Yuna, Rydia, Lilka, Emma
Floor 4: Nash, Mia, Evil Gaia (Laugh all you want, but if Evil Gaia now has the effect of being able to neutralize a PC, that's a large improvement over normal!), A whole slew on reverse (Unsure how that works there...but Billy, Fei, Ziggy, and maybe Hahn?)
Floor 5: Ewan, Johnny, Guido (Lightning Only), Lich Warren
Floor 6: Ghaleon, Fou Lu, Myria 3, Arguably Zophar with his hands
Granted, some of these people have cycled out, and in some battles the weaknesses might not matter, but they can face them a lot. P3 fighters with the less exploited weaknesses really might fare better.