In wano, we were shown how powerful haki users, like kaido and big mom, can use haki to negate DFs. In the case of Kaido and Big Mom, this seems to be a passive ability of theirs; they always have some form of haki defense up, likely being the reason why they are so hard to damage.
However, while this defense prevented Law from teleporting them, there are other abilities that they have clearly shown they cannot negate. Those being awakened DF abilities.
When Kid assigned big mom to the wall, she needed to use physical strength and move the entire wall just to escape Kid's attack. She wasn't able to simply use her haki to negate assign, as Law did to Doc Q's ability. Kid used assign twice on BM, she never showed the ability to negate it.
We see the exact same thing with Law. She could negate teleportation, but she couldn't negate RRoom, an awakened technique. You can't just chalk this up to her being careless. R Room was part of the reason she was defeated, it prevented her from calling her homies that would have been able to save her from the fall. If she could negate it, she would have, but she didn't because she can't.
But lets say we attribute that to "big meme" being "big meme". Surely other, more powerful characters would be able to negate awakening, right? Well....no
Not once did Kaido show the ability to negate Luffy's awakening. All of Luffy's punches turned Kaido's body to rubber. In the finale of their fight when Luffy grabbed kaido to use bajrang gun, Kaido needed to use his flame dragon to get Luffy to release his grip, a grip that was enhanced due to Luffy turning kaido into rubber.
To sum it up, two ACoC users, kaido and big mom, failed to be able to negate awakened DF abilities from the 3 supernova. Why is this important? Because the villain of the next arc, Blackbeard, gets most of his power from DFs.
Some people think Luffy will be able to just use ACoC and negate the yami yami no mi. This might be possible... if Teach isn't awakened. If he is awakened, then even normal ACoC won't be able to negate Teach's powers. If they even can be negated via haki, Luffy will need to unlock some never before seen variant of haki. If I were to guess, we will probably see this variant first being used by Shanks, which will be how Luffy will learn of it.
To sum it up:
- while haki can negate DF effects, awakened DF powers have been shown to be unable to be negated by even the strongest forms of haki(thus far)
- Therefore, it is extremely likely that Teach has or will awaken the yami yami no mi; with this Luffy will be unable to negate Teach's DF with his current haki skillset
- Luffy will need to develop a new variant of haki in order to negate the awakened yami yami no mi
