@Burning
Everlasting said it before I did, lol. And unlike most RPGs, Dark Souls has a second type of poison called "Toxic" that is really nasty when compared to normal poisons. Much harder to heal from and much deadlier, it can kill people under the course of several seconds.
Hmm, I am not sure if there is a weapon that does actual durability negation. If you want high durability piercing, I just need to point at spears and elemental blunt weapons, that are really good against any type of foe, but not true negation. There is the Dark Hand though, that drains life-force out of those captured by it, so there's that.
It increases one's maximum carrying capacity/Lifting Strength. Lorewise, it allowed people to move while using armors so heavy that even superhumans couldn't budge.
Pretty high, with high deflection ratings for several armors and stuff. The problem about Ichigo is that the strength gap is high enough that he may one-shot the Chosen Undead, if he doesn't parries the attack (But he favours dodging over blocking, anyways).
High. Energy attacks would fall upon Magic category, I believe (In fact, Bleach's abilities work in a quite similar way to Dark Souls magic), and with spells like Great Magical Barrier or Vow of Silence (Nullifies any magical power in close proximity), I think he should be able to at least survive Ichigo's energy attacks. Also, Emit Force deflects energetic attacks.
The Chosen Undead wouldn't simply "push" him away, like, with his body. He'd create shockwaves (Like you said, it'd be really dumb of the Chosen Undead's to try to push Ichigo, lol) to do so.
Poison does ignore durability (Toxic too, and Toxic is way nastier and deadlier). Also, he can create acid fogs (Although I must say the acid fog, gameplay wise, only causes severe damage to your enemies' armor and weapons, so idk it would apply to Ichigo's body).
Oh yeah, forgot about Ulquiorra's AOE. Damn, so I guess they're evenly matched.
Looking at Ichigo's profile again, I think Karmic Retribution would only slow him down. Like, really slow him down, but only for some time. CU's best shot at this is using poisons and stuff. He can create illusions, but can Ichigo see invisible and absolutely silent people? If no, then I'm pretty sure CU takes this. If not, then this match is still hard for me to decide.